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Table of Contents | |
Iron is a very critical mineral for persons with thyroid
disease. There is a high association between hyperthyroidism and anemia
and while most of those cases of anemia are from copper deficiency, it is
possible that some of them are from iron deficiency.
Many hypos also seem anemic and it's possible that in
hypothyroidism, anemia stems more often from iron deficiency than from copper
deficiency.
The balance of the three minerals, copper, zinc, and iron,
is critically important in preventing and correcting thyroid diseases.
Each of these three minerals antagonizes and can deplete the other two.
Many times the antagonistic and depletion effects are not due to competition in
absorption, but because these minerals work together.
We can think of these three minerals as corners of a
triangle. Each one affects the other two. If any one of the three is
ingested in large amounts it depletes the other two. Likewise if one of
the three gets deficient, then the other two may not be utilized and therefore
build up in the liver, hair, or other tissues.
For example, if zinc gets too high in the body, copper and
iron will get depleted with the result of anemia and (probably)
hyperthyroidism. If two of the three minerals are high, then the third
mineral will get very depleted. For example, high intake of both iron and
copper could deplete zinc and cause hypothyroidism.
An interesting pair to look at is copper and iron.
Copper and iron work together to form hemoglobin, the oxygen-carrying molecule
in the red blood cell. The two minerals have to be present is a balanced
amount, usually about 5:1, and if one of the two is supplied in higher amounts
it can cause the other to be depleted.
We see this when people take large amounts of iron to
correct anemia. Anemia can be caused by iron deficiency or copper
deficiency (or B-12 or other vitamin deficiencies), but most people and doctors
assume that anemia is always caused by iron deficiency.
Taking large amounts of iron when it is copper that is
deficient will cause copper to be further depleted and lead to a worsening of
the anemia. I believe this is one practice that can lead to
hyperthyroidism. It's possible that the addition of
nutritional supplements like iron to foods may also contribute to thyroid
disease. For example, iron is added to many food products, especially
breakfast cereals, breads, and other grain products. We know that excess
iron will deplete copper, so it's possible that eating iron fortified
foods is a contributing factor to hyperthyroidism.
If one of the pair gets deficient then the other will not
be able to be used effectively and will build up in the liver or other tissues.
For example, if iron gets deficient, then copper may build up in the liver,
hair, and appear as rings or spots in the iris of the eyes. These
accumulations of copper occur in Wilson's Disease, a disease which is described
as a hereditary disease of copper buildup. Whether Wilson's disease is
caused by iron or zinc deficiencies is unknown but many Wilson's patients take
zinc to keep copper levels low (often along with a copper chelator).
There is one subset of hyperthyroids who have high copper
levels in the hair and presumably also have high copper accumulations in the
liver. These people often manifest schizophrenic or manic-depressive
symptoms. In fact one of the characteristics of these psychiatric symptoms
is high copper levels which can be detected in the hair. Also these
conditions are highly associated with hyperthyroidism.
One of the hypotheses that I'm working on is that this
subset of hyperthyroidism, where the person has high copper levels, may be
caused by iron deficiency, with a "functional" copper deficiency
caused because the lack of iron is preventing the copper that is present from
being effectively used. I don't think zinc is deficient in these people
because if that were true, the person would probably be hypothyroid.
What happens when copper and zinc are high and iron gets
depleted? I can tell you from personal experience that bad things
happen. I just went through this through a serious oversight on my part
and my failure to supplement iron along with copper and zinc. I'd like to
relate the story so that others don't have to go through the same problems.
Here's what happened:
At Christmas time I got the flu and it was quite
severe. To mitigate the symptoms and hopefully get over it, I did what I
tell people not to do: I stopped taking iron, because viruses and bacteria
need iron to live, just as we do. This is an effective but unwise strategy
for stopping a cold or flu. Many people do this inadvertently when they
stop eating red meat and then go for years without getting sick. They
think they have become very healthy because they are no longer getting sick, but
what they've actually done is make their body so depleted in iron and copper
that even viruses can't live there. They usually go along happily until
they get hyperthyroidism. I've done this very thing.
When I stopped taking iron, I started developing pains in
my abdomen that concentrated on the left side (left side pain that some people
have reported?). The pains migrated around my left side, sometimes higher,
sometimes lower, sometimes in the front and sometimes in the back. They
seemed to be pains in the liver, pancreas, and kidneys. In addition, I had
pains in the ribs, mostly in the left side but sometimes in the right side,
which seemed to be caused by calcium deficiency, but yet calcium or magnesium
didn't correct the problem. On top of all this I couldn't sleep well and
started getting nighttime rapid heart beat.
These pains got worse and worse over the following months
and on the occasions when I did try iron, I had negative symptoms immediately
afterward. However, after I started looking at iron, I discovered that the
following day is when I got the benefits, while at the time I was concentrating
on the immediate negative effects.
I tried just about every combination of vitamins and
minerals except taking iron but could not figure out what was wrong. I
fasted, went on raw foods, and tried a vegetable only diet. Nothing
helped. Also I noticed that every high copper food was making it
worse. Nuts, beans, chocolate, and beer increased the symptoms so I
discontinued them.
I finally got a critical clue when I went to the mountains
snowboarding. I got out of breath frequently and it reminded me of years
ago when I was anemic. In fact I was anemic. Then I started getting
dizzy and feeling I might faint. The clues were hitting me in the head,
but for some reason I was not paying attention. I think it's because I'm
male and males are not supposed to need iron like females. What I didn't
take into consideration was that I was supplementing copper, about 5 mgs. per
day.
A couple days after returning from the mountains, I had a
dream that all my relatives were coming to visit me because I was dying.
As you can imagine that is a disturbing dream! That morning I got up and the
inspiration came to me to take iron. Within one hour of taking 25 mgs. I
started feeling better, so I took another 25 mgs. I continued to improve
so I took another 50 mgs.
By that night 50% of my symptoms were gone. I slept
through the whole night without waking once, which hadn't happened in many
months. After another day of taking 100 mgs. of iron, 75% of my symptoms
were gone and I again slept the whole night without waking. I was back to
life.
This was a good lesson for me. I recalled that
through the last 20 years whenever I have serious, chronic health problems they
always turn out to be mineral deficiencies. I always think I have some
vitamin deficiency or feel like I'm being poisoned.
I would try all different kinds of vitamins, fast, eat raw
foods, eat only vegetables, eat only potatoes, etc. trying to find the
answer. Then after months of getting worse despite all my efforts I would discover it's a mineral deficiency. I
would take the mineral, feel much better
in only a few hours, and then recover completely over the next couple
weeks. It's taken me a very long time to learn this lesson.
Minerals are the key to health and just about every disease
is the result of mineral deficiencies. When you take the right mineral,
you might feel better in hours or you might feel worse immediately.
However, usually within the next day or two you feel significantly better.
It always amazes me how fast health returns once the right nutrient is supplied
to the body. When we have a mineral deficiency we deteriorate slowly, but
when it is corrected, we improve very fast. Underneath our sickness is a
body crying for nutrients!
ABSORBING IRON
Getting enough iron is difficult for many people. This is probably why iron deficiency is still the number one nutritional deficiency world-wide.
Iron absorption from foods is very limited. The Nutrition Almanac states that only 2 to 10% of the iron in beans, fruits, and vegetables is absorbed. Animal sources of iron are better absorbed. While the body can use several forms of iron, such as ferric or ferrous iron (ferrous is better), the best form is heme iron. Actually heme iron makes other forms of iron more absorbable, so it's probably best to take an iron supplement with a meal of red meat.
Some things can interfere with iron absorption. Lack of hydrochloric acid in the stomach is a big reason. Person on a low salt diet might not be getting enough chlorine (the Cl in NaCl) and therefore not able to produce enough HCl. Taking a good digestive enzyme with the iron supplement should assist the absorption.
Too high an alkaline diet might interfere since iron needs an acid environment. Eat more acid foods with your iron. Too much roughage in the diet can speed up intestinal transit time and reduce iron absorption. Too much coffee, tea, phytates (from grains), oxalates (spinach, rhubarb), and
phosphates can all interfere with iron absorption.
There are nutrients which need to be present for iron absorption: B-12 (try a high potency, 3000 mcg); folic acid (400-800 mcg); vitamin C (1000 mgs); vitamin A; copper; calcium; manganese; molybdenum; and other of the B complex vitamins.
Excessive intake of vitamin E and zinc can interfere with iron absorption. Vitamin E in amounts like 800-1000 IU per day can cause iron deficiency (causing ear aches). Don't take more zinc than iron, since that can also deplete iron.
If all else fails, you might want to experiment with different levels of the B vitamins. It may be that you need more B vitamins and need to get up the the 200 mgs per day quantity. However, I'd try the other things first.
IRON STUDIES
Hemochromatosis is a disease of iron accumulation with
resultant damage to the liver, pancreas, heart, and pituitary.
Premenopausal women are protected from getting it because of menstrual blood
loss. While many people believe it is a hereditary disease, I believe it
is a disease of copper deficiency. When copper
gets deficient, the body can't use iron so it accumulates and causes
damage. The disease is also called siderosis, which is characterized by a gray
pallor to the skin from iron accumulation in the tissue.
The first study concludes "The frequency of thyroid disorders
in men with hemochromatosis is about 80 times that of men in the general
population." What this means is that when men get copper deficient,
they get iron accumulation and thyroid disorders.
I've also seen information that links hemochromatosis to a
deficiency of selenium and copper.
Title
Thyroid disease in hemochromatosis. Increased incidence in homozygous men.
Author
Edwards CQ; Kelly TM; Ellwein G; Kushner JP
- Source
- Arch Intern Med, 143(10):1890-3 1983 Oct
- Abstract
The thyroid function of 49 patients homozygous for the hemochromatosis allele
was studied by measurement of serum thyroxine and thyrotropin concentrations. Of
34 homozygous men, three were found to be hypothyroid (thyroxine, less than 3.0
micrograms/dL and thyrotropin, greater than 40 ImU/mL) and one was hyperthyroid
(thyroxine, 24 micrograms/dL). All 15 homozygous women had normal thyroid
function. The hypothyroid patients had elevated titers of antithyroid
antibodies. Histologic examination of the thyroid at autopsy of one hypothyroid
patient showed notable iron accumulation and fibrosis with modest
lymphocytic infiltration. The causative importance of iron
deposition in thyroid diseases associated with hemochromatosis was suggested by
the reversal of the usual sex ratio of thyroid dysfunction. Men with
hemochromatosis had a much greater iron load than women, and they
also had a surprisingly higher incidence of thyroid disease. Iron
may have caused injury to the thyroid, followed by the development of
antithyroid antibodies and hypothyroidism. The frequency of thyroid disorders
in men with hemochromatosis is about 80 times that of men in the general
population.
- The following study indicates that iron helps to reduce
goiter size. This is excellent evidence that iron is critical for thyroid
function and that iron-deficiency anemia is often an important factor in
causing hypothyroidism.
Eur J Endocrinol 2000 Mar;142(3):217-223 |
|
Iron supplementation in goitrous, iron-deficient
children improves their response to oral iodized oil.
Zimmermann M, Adou P, Torresani T, Zeder C, Hurrell R.
Human Nutrition Laboratory, Swiss Federal Institute of Technology (ETH),
Zurich, Switzerland. michael.zimmermann@ilw.agrl.ethz.ch
OBJECTIVE: In developing countries, many children are at high risk for
both goiter and iron-deficiency anemia. Because iron deficiency may
impair thyroid metabolism, the aim of this study was to determine if
iron supplementation improves the response to oral iodine in goitrous,
iron-deficient anemic children. DESIGN: A trial of oral iodized oil
followed by oral iron supplementation in an area of endemic goiter in
the western Ivory Coast. METHODS: Goitrous, iodine-deficient children
(aged 6-12 years; n=109) were divided into two groups: Group 1 consisted
of goitrous children who were not anemic; Group 2 consisted of goitrous
children who were iron-deficient anemic. Both groups were given 200mg
oral iodine as iodized oil. Thyroid gland volume using ultrasound,
urinary iodine concentration (UI), serum thyroxine (T(4)) and whole
blood TSH were measured at baseline, and at 1, 5, 10, 15 and 30 weeks
post intervention. Beginning at 30 weeks, the anemic group was given
60mg oral iron as ferrous sulfate four times/week for 12 weeks. At 50
and 65 weeks after oral iodine (8 and 23 weeks after completing iron
supplementation), UI, TSH, T(4) and thyroid volume were remeasured.
RESULTS: The prevalence of goiter at 30 weeks after oral iodine in
Groups 1 and 2 was 12% and 64% respectively. Mean percent change in
thyroid volume compared with baseline at 30 weeks in Groups 1 and 2 was
-45.1% and -21.8% respectively (P<0.001 between groups). After iron
supplementation in Group 2, there was a further decrease in mean thyroid
volume from baseline in the anemic children (-34.8% and -38.4% at 50 and
65 weeks) and goiter prevalence fell to 31% and 20% at 50 and 65 weeks.
CONCLUSION: Iron supplementation may improve the efficacy of oral
iodized oil in goitrous children with iron-deficiency anemia.
Title
- The effect of iron supplementation on GSH levels, GSH-Px, and SOD activities
of erythrocytes in L-thyroxine administration.
- Author
- Seymen O; Seven A; Candan G; Yigit G; Hatemi S; Hatemi H
- Address
- Department of Physiology, Cerrahpasa Medical Faculty, Istanbul University,
Turkey.
- Source
- Acta Med Okayama, 51(3):129-33 1997 Jun
- Abstract
- Our aim was to study the effect of iron supplementation on the following
aspects of erythrocyte metabolism in experimental hyperthyroidism: glutathione
(GSH) levels, glutathione peroxidase (GSH-Px), and superoxide
dismutase (SOD) activities. Hyperthyroidism induced by L-thyroxine
administrations significantly raised erythrocyte GSH, GSH-Px and SOD levels of
the rats (P < 0.001). Likewise, we observed that iron supplementation
induced significant rises in erythrocyte GSH, GSH-Px and SOD levels (P <
0.001) as compared with the control group. The erythrocyte GSH, GSH-Px and SOD
levels of hyperthyroidism-induced iron-supplemented animals were significantly
higher when compared with either the iron-supplemented group (P < 0.001) or
the only L-thyroxine-administered hyperthyroid group (P < 0.001, P <
0.05, P < 0.01, respectively). The results of this study show that
L-thyroxine administration and/or iron supplementation increases GSH, GSH-Px
and SOD levels of erythrocytes.
Chung Hua Yu Fang I Hsueh Tsa Chih 1996 Nov;30(6):351-3
[Changes in brain monoamine neurotransmitter in iron deficiency nonanemic
rats].
[Article in Chinese]
Hu R, Wei M, Ding X
Department of Pediatrics Affiliated Hospital, Shandong Medical University,
Jinan.
An iron deficiency nonanemic rat model was established by feeding with
low-iron diet (11.9 mg/kg) to study if there exists biochemical abnormality in
brain tissues. Iron contents of the brain, activities of monoamine oxidase (MAO)
in the corpus striatum, and the contents of monoamine neurotransmitter and its
metabolite in the cerebral cortex and hippocampus were determined by DCP-AES
technique, enzyme histochemical method, and high performance liquid
chromatography with electrochemical detection (HPLC-ECD), respectively. Results
showed that iron contents and activities of MAO in brain tissues of iron
deficiency nonanemic rats reduced significantly, and contents of norepinephrine
(NE) and 5-hydroxytryptamine (5-HT) in cerebral cortex were significantly higher
than those of controls, while 5-hydroxydroxytryptamine acid (5-HIAA) metabolite
of 5-HT in the hippocampus was lower than that of controls. It indicated that
there existed metabolic abnormality of monoamine neurotransmitter in the brain
tissues of iron deficiency nonanemic rats. Also, this study laid a biochemical
basis for abnormal mental and behavioral development caused by iron deficiency.
PMID: 9388911, UI: 98050294
Crit Rev Food Sci Nutr 1999 Mar;39(2):131-48
Iron, thermoregulation, and metabolic rate.
Rosenzweig PH, Volpe SL
University of Massachusetts, Department of Nutrition, Chenoweth Lab, Amherst
01003-1420, USA.
Iron plays an important role, not only in oxygen delivery to the tissues, but
also as a cofactor with several enzymes involved in energy metabolism and
thermoregulation. As a result, much research has been dedicated to understanding
the ramifications of iron depletion and iron deficiency anemia on the
physiological functions of these enzymes. There is evidence to suggest that iron
depletion and iron deficiency anemia cause physiological changes in the body not
only during exercise, but also under resting conditions. Both rat and human
studies have produced results revealing elevated levels of norepinephrine in the
blood and urine of iron-deficient anemic subjects. These studies also provide
evidence to suggest that elevation in metabolic rate may ultimately lead to
slower growth rates and lower body weights in iron-deficient anemic animals and
humans. The focus of this review is on the effects of iron deficiency on
metabolic rate and thermoregulation. Prior to this discussion, a brief
background on iron is presented.
PMID: 10198751, UI: 99214964
-
Redox Rep
1999;4(5):243-50 |
|
Derangement of Kupffer cell functioning and hepatotoxicity in hyperthyroid
rats subjected to acute iron overload.
Boisier X, Schon M, Sepulveda A, Basualdo A, Cornejo P, Bosco C, Carrion Y,
Galleano M, Tapia G, Puntarulo S, Fernandez V, Videla LA
Programas de Farmacologia Molecular y Clinica, Facultad de Medicina,
Universidad de Chile, Santiago.
[Medline record in process]
Liver oxidative stress, Kupffer cell functioning, and cell injury were studied
in control rats and in animals subjected to L-3,3',5-tri-iodothyronine (T3)
and/or acute iron overload. Thyroid calorigenesis with increased rates of
hepatic O2 uptake was not altered by iron treatment, whereas iron enhanced
serum and liver iron levels independently of T3. Liver thiobarbituric acid
reactants formation increased by 5.8-, 5.7-, or 11.0-fold by T3, iron, or
their combined treatment, respectively. Iron enhanced the content of protein
carbonyls independently of T3 administration, whereas glutathione levels
decreased in T3- and iron-treated rats (54%) and in T3Fe-treated animals
(71%). Colloidal carbon infusion into perfused livers elicited a 109% and 68%
increase in O2 uptake in T3 and iron-treated rats over controls. This
parameter was decreased (78%) by the joint T3Fe administration and abolished
by gadolinium chloride (GdCl3) pretreatment in all experimental groups.
Hyperthyroidism and iron overload did not modify the sinusoidal efflux of
lactate dehydrogenase, whereas T3Fe-treated rats exhibited a 35-fold increase
over control values, with a 54% reduction by GdCl3 pretreatment. Histological
studies showed a slight increase in the number or size of Kupffer cells in
hyperthyroid rats or in iron overloaded animals, respectively. Kupffer cell
hypertrophy and hyperplasia with presence of inflammatory cells and increased
hepatic myeloperoxidase activity were found in T3Fe-treated rats. It is
concluded that hyperthyroidism increases the susceptibility of the liver to
the toxic effects of iron, which seems to be related to the development of a
severe oxidative stress status in the tissue, thus contributing to the
concomitant liver injury and impairment of Kupffer cell phagocytosis and
particle-induced respiratory burst activity.
PMID: 10731099, UI: 20193365
-
: J Basic Clin Physiol Pharmacol 1999;10(4):315-25 |
|
Evaluation of antioxidant status in liver tissues: effect of iron
supplementation in experimental hyperthyroidism.
Seymen HO, Seven A, Civelek S, Yigit G, Hatemi H, Burcak G
Department of Physiology, Cerrahpasa Medical Faculty, Istanbul University,
Turkey. seymano@yahoo.com
The antioxidant defense system in liver tissue in experimental hyperthyroidism
and/or in iron supplementation was investigated. Thyroid hormones (T3, T4,
TSH), ferritin (marker of iron status), antioxidant status components
(glutathione [GSH], glutathione peroxidase [GSH-Px], superoxide dismutase
[SOD]), and serum transaminases (GOT and GPT, both of which are known to be
released from damaged hepatocytes), were measured. Hyperthyroidism in rats,
induced by L-thyroxine administration, significantly raised SOD activity (p
< 0.05), but significantly decreased GSH-Px activity and GSH values (p <
0.001) in the liver. In the L-thyroxine administered and iron supplemented
(TI) group, GSH and GSH-Px values of liver tissues were significantly lower
than those of control rats (p < 0.05). GSH-Px levels of the TI group were
higher (p < 0.001), and SOD levels significantly lower (p < 0.001) than
those of the L-thyroxine administered group. We conclude that hyperthyroidism
induces SOD activity in liver; ferritin levels increase in hyperthyroidism,
contributing to the antioxidant defense system; GSH-Px and GSH levels are
decreased significantly in hyperthyroidism either due to inactivation due to
increased oxidative stress or to insufficient synthesis; iron supple- and GPT
analysis); iron decreases the effect of T4. This must be taken into
consideration during iron supplementation.
PMID: 10631595, UI: 20097170
-
: South Med J 1997 Jun;90(6):637-9 |
|
Ferrous sulfate-induced increase in requirement for thyroxine in a
patient with primary hypothyroidism.
Shakir KM, Chute JP, Aprill BS, Lazarus AA
Department of Internal Medicine, National Naval Medical Center, Bethesda, MD
20889-5600, USA.
Recent studies have shown that under experimental conditions ferrous sulfate
may reduce the gastrointestinal absorption of orally administered
levothyroxine sodium in patients with primary hypothyroidism. We describe a
patient who became hypothyroid while taking ferrous sulfate. The hypothyroid
status was corrected by increasing the dose of levothyroxine. Subsequently,
when ferrous sulfate was discontinued, the patient became hyperthyroid while
taking the higher dose of thyroid hormone preparation. Since both
hypothyroidism and iron deficiency anemia may coexist, additional thyroid
function testing is recommended in patients treated concurrently with
ferrous sulfate and L-thyroxine.
PMID: 9191742, UI: 97335076
-
: J Biol Chem 1996 May 17;271(20):12017-23 |
|
Thyroid hormone modulates the interaction between iron regulatory
proteins and the ferritin mRNA iron-responsive element.
Leedman PJ, Stein AR, Chin WW, Rogers JT
Department of Medicine, Brigham and Women's Hospital, Harvard Medical
School, Boston, Massachusetts 02115, USA.
The cytoplasmic iron regulatory protein (IRP) modulates iron homeostasis by
binding to iron-responsive elements (IREs) in the transferrin receptor and
ferritin mRNAs to coordinately regulate transferrin receptor mRNA stability
and ferritin mRNA translational efficiency, respectively. These studies
demonstrate that thyroid hormone (T3) can modulate the binding activity of
the IRP to an IRE in vitro and in vivo. T3 augmented an iron-induced
reduction in IRP binding activity to a ferritin IRE in RNA electrophoretic
mobility shift assays using cytoplasmic extracts from human liver hepatoma
(HepG2) cells. Hepatic IRP binding to the ferritin IRE also diminished after
in vivo administration of T3 with iron to rats. In transient transfection
studies using HepG2 cells and a human ferritin IRE-chloramphenicol
acetyltransferase (H-IRE-CAT) construct, T3 augmented an iron-induced
increase in CAT activity by approximately 45%. RNase protection analysis
showed that this increase in CAT activity was not due to a change in the
steady state level of CAT mRNA. Nuclear T3-receptors may be necessary for
this T3-induced response, because the effect could not be reproduced by the
addition of T3 directly to cytoplasmic extracts and was absent in CV-1 cells
which lack T3-receptors. We conclude that T3 can functionally regulate the
IRE binding activity of the IRP. These observations provide evidence of a
novel mechanism for T3 to up-regulate hepatic ferritin expression, which may
in part contribute to the elevated serum ferritin levels seen in
hyperthyroidism.
PMID: 8662626, UI: 96216126
- The following study describes a 62-year old male with
sideroblastic anemia, which is anemia with excessive iron deposition in the
liver and other cells of the body, and hyperthyroidism. My analysis of
this is that the man had a copper deficiency which created the iron build-up
and the hyperthyroidism.
-
Medicina (B Aires)
1995;55(6):693-6 |
|
[Acquired sideroblastic anemia and cholestasis in a hyperthyroid patient
treated with methimazole and atenolol].
[Article in Spanish]
Mamianetti A, Munoz A, Ronchetti RD, Maccione E, Poggi U, Mugnolo R, Gallo O
Departamento de Medicina Interna, Hospital Aeronautico Central, Buenos
Aires, Argentina.
The authors describe a 62 year-old white male who was diagnosed as
autoimmune hyperthyroidism and treated with methimazole and atenolol. Ten
days later he showed itching, jaundice and choluria. All drugs were
discontinued. The patient was given radioactive iodine. Two months later
direct serum bilirubin levels reached 35 mg%. Endoscopic retrograde
cholangiogram evidenced normal extrahepatic biliary ducts. The percutaneous
liver biopsy showed marked cholestasis specially in the centrolobular zone
with a slight infiltrate of mononuclear cells in the portal areas. Together
with the liver disease the patient presented an anemic syndrome. Bone marrow
aspiration showed rich cellularity, Perls staining showed 70% sideroblasts,
with 10% ringed sideroblasts and increased extracorpuscular iron. The
patient's evolution was satisfactory. Twenty months after the beginning of
the disease clinical and biochemical tests were normal. A new bone marrow
aspiration rendered normal. Hepatic cholestasis suffered by our patient was
probably due to an adverse reaction of methimazole. Physiopathology of
reversible sideroblastic anemia is discussed.
PMID: 8731582, UI: 96340505
- Ferritin is a combination of iron and apoferritin, which
is an iron-transporting protein. In the following study it is noted that
serum ferritin levels increase in hyperthyroidism, meaning that there is
excess iron. In fact, the serum ferritin
levels of four anemic patients were significantly higher than those
of nine nonanemic patients. (I'll bet the researchers couldn't
figure that one out!)
-
- I believe that ferritin levels are high because of a
copper deficiency and that once the thyroid hormone levels are decreased
(through antithyroid medication), copper is not being used up to de-activate
the hormones, and copper levels increase. This decreases the ferritin
level and increases hemoglobin (because the iron now has copper to combine
with to form hemoglobin).
-
Clin Investig 1993 Dec;72(1):26-9 |
|
Evaluation of increased serum ferritin levels in patients with
hyperthyroidism.
Kubota K, Tamura J, Kurabayashi H, Shirakura T, Kobayashi I
Department of Medicine, Kusatsu Branch Hospital, Gunma, Japan.
To further elucidate the mechanism of increased serum ferritin levels in
hyperthyroidism, the changes in erythrocytes and serum iron and total
iron-binding capacity levels were examined in addition to serum ferritin
levels in 13 hyperthyroid patients. The mean values of hemoglobin, red
blood cells, and packed cell volume were increased by antithyroid therapy.
While the serum levels of iron did not change, those of total iron-binding
capacity increased significantly after achieving a euthyroid state.
Increased serum ferritin levels returned to normal through antithyroid
therapy. Furthermore, the serum ferritin levels of four anemic patients were
significantly higher than those of nine nonanemic patients. Thus it is
concluded that the increase in serum ferritin levels in patients with
hyperthyroidism may be due to the direct action of thyroid hormones on its
synthesis, while in some cases complicated with anemia impaired iron
utilization by erythropoietic cells may also be involved.
PMID: 8136612, UI: 94184112
- The following study shows that liver ferritin synthesis
is not elevated in hypothyroidism as it is in hyperthyroidism. This
indicates that copper is not made deficient by experimental hypothyroidism
induced by PTU.
-
: Thyroidology 1992 Dec;4(3):93-7 |
|
Relation between thyroid status and ferritin metabolism in rats.
Deshpande UR, Nadkarni GD
Radiation Medicine Centre, B.A.R.C., Bombay, India.
Rats were made hypo and 'hyperthyroid' with propylthiouracil (PTU) and
L-Thyroxine (L-T) respectively. The hypo and hyperthyroid status in these
rats were confirmed by serum level of T4 and T3. Liver iron was
significantly increased in both the hypo and hyperthyroid animals. However,
liver ferritin synthesis rate was reduced by 36% in hypothyroid rats, and
elevated by 38% in hyperthyroid ones. A similar trend was seen in liver
ferritin concentration. Further, serum transaminases were elevated only in
animals of the hyperthyroid group. It appears from the present data that
ferritin metabolism is influenced by thyroid hormone as well as by iron.
Thus, the raised serum ferritin in hyperthyroid patients may be partially
attributed to increased ferritin synthesis in the liver and its possible
leakage into circulation.
- Iron is used for staining tissue for the demonstration
of glycosaminoglycan (GAG) deposition in the skin, which is seen in
pretibial myxedema of Graves' Disease. I'm not sure exactly what this
means at this point but hope to fit this in at some time.
-
J Histochem Cytochem 1984 Oct;32(10):1121-4 |
|
Histochemical evaluation of glycosaminoglycan deposition in the skin.
Kupchella CE, Matsuoka LY, Bryan B, Wortsman J, Dietrich JG
Histologic demonstration of glycosaminoglycan (GAG) deposition in the
skin has been based on the use of either colloidal iron or alcian blue.
To define the best technique for the determination of skin GAG content we
undertook a prospective study comparing the two stains and evaluating the
use of cetylpyridinium chloride (CPC) to enhance fixation. Slides were
prepared from skin biopsies obtained from five patients with cutaneous
mucinoses. The preparations were coded and examined by three observers.
Colloidal iron staining gave a higher intensity for GAG deposits in
papillary and reticular dermis. Digestion by specific enzymes identified
similar GAGs with either colloidal iron, or alcian blue; however, colloidal
iron made GAGs more obvious, partly due to the contrast afforded by the
yellow background stain. The addition of CPC to the fixative appreciably
enhanced GAG fixation without interfering with the action of enzymes.
Experimentally, we confirmed this effect of CPC by determining a pronounced
decrease in GAG leakage into the fixative from CPC treated human umbilical
cord. We conclude that the combination of CPC fixation and colloidal iron
staining gives the best definition of skin GAGs in clinical specimens.
- The following study concludes "that during
thyrotoxicosis the supply of iron into erythroblasts is greater than the
amount used for haemoglobin synthesis." Since hemoglobin
production also requires copper, this is indicative of a copper deficiency
in hyperthyrodism.
-
Scand J Haematol 1980 Sep;25(3):237-43 |
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Sideroblasts and haemosiderin in thyrotoxicosis.
Lahtinen R
Bone marrow sideroblasts and haemosiderin were studied in 19 thyrotoxic
patients before therapy and in the euthyroid state. The proportion of
sideroblasts and the amount of haemosiderin were significantly higher in the
hyperthyroid than in the euthyroid phase. Pathological sideroblasts with
coarse perinuclear iron granules were found before therapy but not in the
euthyroid phase. It is concluded that during thyrotoxicosis the supply of
iron into erythroblasts is greater than the amount used for haemoglobin
synthesis.
- Because aluminum interferes with iron metabolism, studies have found
that people who eat food cooked in aluminum pots get anemia. Getting
these people to switch to iron cookware greatly reduces the rate of anemia.
-
Lancet 1999 Feb 27;353(9154):712-6 |
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Effect of consumption of food cooked in iron pots on iron status and growth
of young children: a randomised trial.
Adish AA, Esrey SA, Gyorkos TW, Jean-Baptiste J, Rojhani A
School of Dietetics and Human Nutrition, McGill University, St
Anne-de-Bellevue, Quebec, Canada.
BACKGROUND: In less-developed countries, novel strategies are needed to
control iron-deficiency anaemia, the most common form of malnutrition.
METHODS: We undertook a community-based randomised controlled trial to
assess the effects of iron or aluminium cooking pots in young Ethiopian
children. Analysis was by intention-to-treat. The primary outcomes were
change in children's haemoglobin concentration, weight, or length over the
study period. We also did a laboratory study of total and available iron in
traditional Ethiopian foods cooked in iron, aluminium, and clay pots.
FINDINGS: 407 children, one per household, entered the study. The change in
haemoglobin concentration was greater in the iron-pot group than in the
aluminium-pot group (mean change to 12 months 1.7 [SD 1.5] vs 0.4 [1.0] g/dL;
mean difference between groups 1.3 g/dL [95% Cl 1.1-1.6]). The mean
differences between the groups in weight and length gain to 12 months
(adjusted for baseline weight or length) were 0.6 cm (95% CI 0.1-1.0) and
0.1 kg (-0.1 to 0.3). The laboratory study showed that total and available
iron was greatest in foods cooked in iron pots, except for available iron in
legumes for which there was no difference between types of pot.
INTERPRETATION: Ethiopian children fed food from iron pots had lower rates
of anaemia and better growth than children whose food was cooked in
aluminium pots. Provision of iron cooking pots for households in
less-developed countries may be a useful method to prevent iron-deficiency
anaemia.
Iron deficiency may be a factor in anemia,
hypothyroidism, and myxedema (pretibial myxedema is a swelling of the front
of the shin from fibroblast proliferation, a condition associated with
thyroid disease and thyroid eye disease). There are not many
studies which have looked at iron levels in myxedema, but the following
study is suggestive.
-
Lik Sprava 1999 Jun;(4):148-50 |
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[Iron-deficiency anemia as a hematological mask of myxedema].
[Article in Ukrainian]
Vydyborets' SV
An atypical course of myxedema manifested by iron-deficiency anemia is
described that proved to be a diagnostic challenge. Pathogenetic mechanisms
of origination are analyzed.
-
Eur J Endocrinol 2000 Mar;142(3):217-23 |
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Iron supplementation in goitrous, iron-deficient children
improves their response to oral iodized oil.
Zimmermann M, Adou P, Torresani T, Zeder C, Hurrell R
Human Nutrition Laboratory, Swiss Federal Institute of Technology (ETH),
Zurich, Switzerland. michael.zimmermann@ilw.agrl.ethz.ch
OBJECTIVE: In developing countries, many children are at high risk for both
goiter and iron-deficiency anemia. Because iron deficiency may impair
thyroid metabolism, the aim of this study was to determine if iron
supplementation improves the response to oral iodine in goitrous,
iron-deficient anemic children. DESIGN: A trial of oral iodized oil followed
by oral iron supplementation in an area of endemic goiter in the western
Ivory Coast. METHODS: Goitrous, iodine-deficient children (aged 6-12 years;
n=109) were divided into two groups: Group 1 consisted of goitrous children
who were not anemic; Group 2 consisted of goitrous children who were
iron-deficient anemic. Both groups were given 200mg oral iodine as iodized
oil. Thyroid gland volume using ultrasound, urinary iodine concentration
(UI), serum thyroxine (T(4)) and whole blood TSH were measured at baseline,
and at 1, 5, 10, 15 and 30 weeks post intervention. Beginning at 30 weeks,
the anemic group was given 60mg oral iron as ferrous sulfate four times/week
for 12 weeks. At 50 and 65 weeks after oral iodine (8 and 23 weeks after
completing iron supplementation), UI, TSH, T(4) and thyroid volume were
remeasured. RESULTS: The prevalence of goiter at 30 weeks after oral iodine
in Groups 1 and 2 was 12% and 64% respectively. Mean percent change in
thyroid volume compared with baseline at 30 weeks in Groups 1 and 2 was
-45.1% and -21.8% respectively (P<0.001 between groups). After iron
supplementation in Group 2, there was a further decrease in mean thyroid
volume from baseline in the anemic children (-34.8% and -38.4% at 50 and 65
weeks) and goiter prevalence fell to 31% and 20% at 50 and 65 weeks. CONCLUSION:
Iron supplementation may improve the efficacy of oral iodized oil in
goitrous children with iron-deficiency anemia.
-
- The following study sheds light on the situation faced when the patient
cannot tolerate taking thyroid replacement hormone. The person
experiences rapid heart beat and palpitations. This indicates that the
person is probably anemic from iron deficiency and will tolerate thyroxin
when the anemia is corrected.
-
Mayo Clin Proc 2000 Feb;75(2):189-92 |
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Anemia: a cause of intolerance to thyroxine sodium.
Shakir KM, Turton D, Aprill BS, Drake AJ 3rd, Eisold JF
Department of Internal Medicine, National Naval Medical Center, Bethesda,
Md., 20889-5600, USA.
Usual causes of intolerance to thyroxine sodium include coronary artery
disease, advanced age, untreated adrenal insufficiency, and severe
hypothyroidism. We describe 4 patients with iron deficiency anemia and
primary hypothyroidism. After treatment with thyroxine sodium, these
patients developed palpitations and feelings of restlessness, which
necessitated discontinuation of the thyroid hormone. After the anemia was
treated with ferrous sulfate for 4 to 7 weeks, they were able to tolerate
thyroxine sodium therapy. Iron deficiency anemia coexisting with primary
hypothyroidism results in a hyperadrenergic state. In such patients, we
postulate that thyroid hormone administration causes palpitations,
nervousness, and feelings of restlessness. Correction of any existing
pronounced anemia in hypothyroid patients who are intolerant to thyroxine
sodium therapy may result in tolerance to this agent.
-
J Nutr 1998 Aug;128(8):1401-8 |
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Plasma thyroid hormone kinetics are altered in
iron-deficient rats.
Beard JL, Brigham DE, Kelley SK, Green MH
Nutrition Department, The Pennsylvania State University, University Park, PA
16802, USA.
Iron deficiency anemia is associated with lower plasma thyroid hormone
concentrations in rodents and, in some studies, in humans. The objective of
this project was to determine if plasma triiodothyronine (T3) and thyroxine
(T4) kinetics were affected by iron deficiency. Studies were done at a near-thermoneutral
temperature (30 degrees C), and a cool environmental temperature (15 degrees
C), to determine plasma T3 and T4 kinetics as a function of dietary iron
intake and environmental need for the hormones. Weanling male Sprague-Dawley
rats were fed either a low Fe diet [iron-deficient group (ID), <5
microg/g Fe] or a control diet [control group (CN), 35 microg/g Fe] at each
temperature for 7 wk before the tracer kinetic studies. An additional ID
group receiving exogenous thyroid hormone replacement was also used at the
cooler temperature. For T4, the disposal rate was >60% lower (89 +/- 6
vs. 256 +/- 53 pmol/h, P < 0.001) in ID rats than in controls at 30
degrees C, and approximately 40% lower (192 +/- 27 vs. 372 +/- 26 pmol/h, P
< 0.01) in ID rats at 15 degrees C. Exogenous T4 replacement in a cohort
of ID rats at 15 degrees C normalized the T4 concentration and the disposal
rate. For T3, the disposal rate was significantly lower in ID rats in a cool
environment (92 +/- 11 vs. 129 +/- 11 pmol/h, P < 0.01); thyroxine
replacement again normalized the T3 disposal rate (126 +/- 12 pmol/h).
Neither liver nor brown fat thyroxine 5'-deiodinase activities were
sufficiently different to explain the lower T3 disposal rates in iron
deficiency. Thus, plasma thyroid hormone kinetics in iron deficiency anemia
are corrected by simply providing more thyroxine. This suggests a central
regulatory defect as the primary lesion and not peripheral alterations.
-
- [From iodine deficiency to goiter. Pathophysiology of iron deficiency
goiter].
Internist (Berl). 1998 Jun;39(6):566-73. Review. German. No
abstract available.
PMID: 9677510; UI: 98342474
-
Am J Clin Nutr 2000 Jan;71(1):88-93 |
t |
Persistence of goiter despite oral iodine supplementation
in goitrous children with iron deficiency anemia in Cote d'Ivoire.
Zimmermann M, Adou P, Torresani T, Zeder C, Hurrell R
Human Nutrition Laboratory, Swiss Federal Institute of Technology, Zurich,
Switzerland. michael.zimmermann@ilw.agrl.ethz.ch
BACKGROUND: In developing countries, many children are at high risk of
goiter and iron deficiency anemia. Because iron deficiency can have adverse
effects on thyroid metabolism, iron deficiency may influence the response to
supplemental iodine in areas of endemic goiter. OBJECTIVE: The aim of this
study was to determine whether goitrous children with iron deficiency anemia
would respond to oral iodine supplementation. DESIGN: A trial of oral iodine
supplementation was carried out in an area of endemic goiter in western Cote
d'Ivoire in goitrous children (n = 109) aged 6-12 y. Group 1 (n = 53)
consisted of goitrous children who were not anemic. Group 2 (n = 56)
consisted of goitrous children who had iron deficiency anemia. At baseline,
thyroid gland volume and urinary iodine, thyrotropin, and thyroxine were
measured by using ultrasound. Each child received 200 mg I orally and was
observed for 30 wk, during which urinary iodine, thyrotropin, thyroxine,
hemoglobin, and thyroid gland volume were measured. RESULTS: The prevalence
of goiter at 30 wk was 12% in group 1 and 64% in group 2. The mean
percentage change from baseline in thyroid volume 30 wk after administration
of oral iodine was -45.1% in group 1 and -21.8% in group 2 (P < 0.001).
Among the anemic children, there was a strong correlation between the
percentage decrease in thyroid volume and hemoglobin concentration (r(2) =
0.65). CONCLUSION: The therapeutic response to oral iodine was impaired in
goitrous children with iron deficiency anemia, suggesting that the presence
of iron deficiency anemia in children limits the effectiveness of iodine
intervention programs.
-
Bolus of Deferoxamine Reduces Ferritin Levels in Patients
With Iron Overload
WESTPORT, May 08 (Reuters Health) - Bolus injection of deferoxamine decreases
serum ferritin concentrations in patients with iron overload, researchers in
Italy report in the May 1st issue of Blood.
Dr. Massimo Franchini, of Ospedale Policlinico in Verona, and colleagues
studied 27 adults with iron overload due to various conditions or treatments.
Initial comparison of two doses of deferoxamine, given subcutaneously 12 hours
apart, and a 12-hour subcutaneous infusion of deferoxamine showed that mean
48-hour urinary iron excretion was similar for both types of administration.
Twenty-six patients continued therapy with bolus injection, and the
researchers measured serum ferritin concentrations at various times up to a mean
of about 20 months. Overall, ferritin concentrations dropped from an average of
1631.5 micrograms/L to below 1,000 micrograms/L in 73% of patients, below 500
micrograms/L in 42% of patients, and to normal levels in 26% of patients.
Dr. Franchini's group notes that patients who did not receive blood
transfusions during deferoxamine therapy had a significantly larger decrease in
mean serum ferritin concentration compared with patients who regularly had
transfusions. Ferritin concentrations did not reach normal levels in any
patients who had transfusions.
The authors caution that measuring serum ferritin is not an accurate way of
measuring iron stores, and that the two methods of administering deferoxamine
should be compared with respect to levels of free iron.
However, they believe that the results "support the need for a
prospective, randomized controlled trial in a larger and more homogenous
population of patients in which hepatic, cardiac, and endocrine functions are
systematically assessed."
Blood 2000;95:2776-2779.
- The following study offers support for a copper deficiency in
hyperthyroidism since iron has enhanced toxicity to the liver in
hyperthyroidism. Low copper allows free iron which is uncoupled to copper to
be more toxic.
Redox Rep 1999;4(5):243-50 |
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Derangement of Kupffer cell functioning and
hepatotoxicity in hyperthyroid rats subjected to acute iron overload.
Boisier X, Schon M, Sepulveda A, Basualdo A, Cornejo P, Bosco C, Carrion
Y, Galleano M, Tapia G, Puntarulo S, Fernandez V, Videla LA
Programas de Farmacologia Molecular y Clinica, Facultad de Medicina,
Universidad de Chile, Santiago.
Liver oxidative stress, Kupffer cell functioning, and cell injury were
studied in control rats and in animals subjected to
L-3,3',5-tri-iodothyronine (T3) and/or acute iron overload. Thyroid
calorigenesis with increased rates of hepatic O2 uptake was not altered by
iron treatment, whereas iron enhanced serum and liver iron levels
independently of T3. Liver thiobarbituric acid reactants formation increased
by 5.8-, 5.7-, or 11.0-fold by T3, iron, or their combined treatment,
respectively. Iron enhanced the content of protein carbonyls independently
of T3 administration, whereas glutathione levels decreased in T3- and
iron-treated rats (54%) and in T3Fe-treated animals (71%). Colloidal carbon
infusion into perfused livers elicited a 109% and 68% increase in O2 uptake
in T3 and iron-treated rats over controls. This parameter was decreased
(78%) by the joint T3Fe administration and abolished by gadolinium chloride
(GdCl3) pretreatment in all experimental groups. Hyperthyroidism and iron
overload did not modify the sinusoidal efflux of lactate dehydrogenase,
whereas T3Fe-treated rats exhibited a 35-fold increase over control values,
with a 54% reduction by GdCl3 pretreatment. Histological studies showed a
slight increase in the number or size of Kupffer cells in hyperthyroid rats
or in iron overloaded animals, respectively. Kupffer cell hypertrophy and
hyperplasia with presence of inflammatory cells and increased hepatic
myeloperoxidase activity were found in T3Fe-treated rats. It is concluded
that hyperthyroidism increases the susceptibility of the liver to the toxic
effects of iron, which seems to be related to the development of a severe
oxidative stress status in the tissue, thus contributing to the concomitant
liver injury and impairment of Kupffer cell phagocytosis and
particle-induced respiratory burst activity.
- IRON DEFICIENCY AND THERMOREGULATION
The following studies offer evidence that the inability to maintain body
temperature (feeling cold when others are warm) is due to iron deficiency. Most
hypos experience this, indicating that iron deficiency is usually a factor in
hypothyroidism.
IRON DEFICIENCY AND SUPPLEMENTATION IMPACT THERMOREGULATION AND BROWN ADIPOSE
TISSUE (BAT) MITOCHONDRIAL MORPHOLOGY OF RATS EXPOSED TO COLD
Author(s):
MICHELSEN KIM G HALL CLINTON B NEWMAN JR SAMUEL M DROKE ELIZABETH A SLEEPER
MARY E LUKASKI HENRY C
Interpretive Summary:
The role that iron (Fe) plays in regulating whole-body temperature is not
well defined. Fe-deficient rats have reduced concentrations of thyroid hormones
and altered body temperature. Because thyroid hormones act at the mitochondria
level of brown adipose tissue to produce heat, Fe status may affect the
structural characteristics of mitochondria, a cell component that produces
energy to maintain body temperature. To examine the relationships among dietary
iron, body temperature, thyroid hormones, and brown adipose tissue mitochondria,
young male rats were fed diets containing adequate or deficient amounts of Fe.
Some of the rats fed the low-Fe diets then were given the diet containing an
adequate amount of Fe. When exposed to cold air for four hours, the rats fed the
Fe-deficient diet had a greater decline in body temperature than the rats fed
the Fe- adequate diet. The rats initially fed the Fe-deficient diet then fed the
Fe-adequate diet had similar body temperatures as the animals fed the Fe-
adequate diet. Plasma thyroid hormone concentrations were less in the rats fed
the Fe-deficient, as compared to the Fe-adequate and Fe-deficient supplemented
with adequate Fe diets. The structure of mitochondria suggests that Fe
deficiency produced changes that indicate impaired heat production; this change
was ameliorated with Fe supplementation. These findings indicate that Fe
deficiency reduces the capability of rats to maintain body temperature during
short-term cold exposure. Biological impairments of Fe deficiency lie in the
production of adequate amounts of thyroid hormones and adverse changes in the
mitochondria that inhibit the production of heat. This information will be
useful to scientists who seek to understand how mineral elements regulate energy
utilization.
See also:
http://www.nap.edu/books/0309054842/html/248.html
IRON DEFICIENCY
Several key observations have stimulated interest in the relationship
between iron deficiency and thermoregulation. Iron-deficient anemic rats
were found to be unable to maintain normal body temperature when exposed to
cold (39°F [4°C]) (Beard et al., 1982, 1984; Dillmann et al., 1979, 1980).
Accompanying the impairment in thermoregulation were a decrease in the rate
of thyroid hormone turnover and an increase in the rate of norepinephrine
turnover, as compared to those observed in noniron-depleted cold-exposed
(control) rats. Iron-deficient humans are unable to maintain their body
temperature during exposure to cool water (82°F [28°C]) (Beard et al.,
1990a; Martinez-Torres et al., 1984) or cool air (61°F [16°C]) (Lukaski et
al., 1990), compared to subjects with normal iron status and equivalent body
composition. Additionally, the iron-deficient subjects had lower thyroid
hormone (Beard et al., 1990a) and higher catecholamine responses to cold
(Lukaski et al., 1990; Martinez-Torres et al., 1984), similar to the
response of iron-deficient rats. After repletion with iron supplements, the
previously iron-deficient human subjects showed improved ability to maintain
body temperature in the cold. These observations clearly demonstrate the
link between iron deficiency and poor thermoregulation.
Anemia vs. Tissue Iron Deficiency
Iron deficiency may exert its effects on thermoregulation through two
distinct, yet related, mechanisms, one involving anemia and the other
involving tissue iron deficiency. Iron-deficiency anemia results in
decreased oxygen transport from the lungs to tissues, and this reduction in
oxygen availability inhibits physiological responses to cold, including
peripheral vasoconstriction, a heat-conserving process, and increased
metabolic rate, a heat-generating process. Hypoxia, created by reducing the
oxygen content or the pressure of inspired air, results in hypothermia in
rodents (Gautier et al., 1991). The inability to conserve and produce body
heat properly accounts for hypoxia-induced hypothermia (Wood, 1991). Lack of
oxygen availability for aerobic metabolism causes a decrease in metabolic
rate and, subsequently, a decrease in heat production. Hypoxic rats
demonstrate decreased shivering and nonshivering thermogenesis (Gautier et
al., 1991) and a decrease in body temperature set-point (Gordon and
Fogelson, 1991). Impaired neural control of these processes may also account
for the effects of hypoxia on thermoregulation (Mayfield et al., 1987).
Tissue iron deficiency, apart from anemia, decreases the ability of muscles
to utilize energy for muscular contraction, presumably via a decrease in the
activity of mitochondrial iron-containing enzymes required for the oxidative
production of ATP (Davies et al., 1984).
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