Iron metabolism by Dr Anurag Yadav

Iron metabolism - discussed under the headings of distribution, sources, RDA, Absorption, Mucosal block mechanism, deficiency manifestation, clinical features, laboratory findings, treatment and toxicity.
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1. Iron Metabolism
MNR MEDICAL COLLEGE & HOSPITAL
Dr Anurag Yadav
MBBS, MD
Assistant Professor
Department of Biochemistry
Instagram page –biochem365

2. Distribution
●Total body iron content is 3 to 5 g; 75% of which is in
blood, the rest is in liver, bone marrow and muscles.
●Iron is present in almost all cells.
●Blood contains 14.5 g of Hb per 100 mL.
●About 75% of total iron is in hemoglobin, and 5% is in
myoglobin and 15% in ferritin.

3. Iron containing proteins
Hemoglobin
Myoglobin
Cytochrome oxidase
Cytochrome b, b5
Cytochrome c, c1
Cytochrome p450
Xanthine oxidase
Nitric oxide synthase
Aconitase
Ferritin
Transferrin

4. Requirement of Iron
●Daily 20mg of iron in Indian adult.
Westerns require 15mg/day as their diet donotcontain much
phytates.
●Of which only 1-2mg is absorbed.
●Children between 13–15 years need 20–30 mg/day.
●Pregnant women need 40 mg/day.
●First 3 month of life, iron intake is negligible because the
milk is poor reserve.

5. Source of iron
●Leafy vegetables (20mg/100g)
●Pulses (10mg/100g)
●Cereals (5mg/100g)
●Liver (5mg/100g)
●Meat (2mg/100g)
●Jaggery
●Iron utensil
●Milk-very poor source (0.1mg/100ml).

6. Factors influencing the absorption
●Reduced iron form-Only Fe++ (ferrous) form (reduced
form) is absorbed. .
●Fe+++ (ferric) form is not absorbed.
●Ascorbic acid: Ferric ions are reduced with the help of
gastric HCl, ascorbic acid, cysteineand -SH groups of
proteins. Therefore, these will favoriron absorption.
●Interfering substances: phyticacids, oxalic acids.
●Other minerals: calcium, lead, phosphates, copper.

7. MUCOSAL BLOCK THEORY
●Site of absorption: Duodenum and jejunum.
●Iron metabolism is unique = homeostasis is regulated at
level of absorption. NOT by excretion.
●No other nutrient is regulated in this manner.
●The iron is termed as one-way element.
●When iron stores is depleted, absorption is enhanced and
when adequate quantity of iron is stored than absorption
is decreased.
●This is termed as mucosal block regulation.

10. Mucosal block theory

12. Regulation of absorption by four mechanism
●Mucosal regulation
●Hepcidin
●Stores regulation
●Erythropoieticregulation
●Synthesis of ferritin and transferrin receptors

13. Iron transport in blood and Uptake by cells
Transport form is TRANSFERRIN.
Uptake is dependent on the transferrin receptors of body
cells.

14. Storage of iron.
Storage form is FERRITIN

15. Excretion of iron:
Most of the iron is conserved by using the haptoglobins.
Iron is one-way element.
No iron is excreted by the urine.
Any type of bleeding will cause iron loss.

16. Iron deficiency anemia
This most common nutritional deficiency disorder leaves
about 30% of world population anemic.
About 70% of Indians have iron deficiency and 85% of
pregnant women suffer from iron deficiency anemia.

17. Causes of iron deficiency
Nutritional deficiency of iron
Hookworm infestation
Repeated pregnancy
Chronic blood loss
Nephrosis
Lack of absorption
Lead poisoning

18. Clinical manifestation:
Apathy
Weakness
Plummer-wilsonsyndrome-dysphagia
Irritability
Lowered memory
Impaired attention
koilonychia(Spoon nail)

20. Laboratory findings
Low serum iron levels = 50-150microg/dl
Elevated TIBC = 400microg/dL
Increased levels of Transferrin receptors levels

21. Treatment of iron deficiency
Oral iron supplementations. 100mg of Fe and Folic acid =
pregwomen
Vitamin C given along. (Fe3+ = Fe2+)

22. Toxicity :
>50mg/day = nausea, diarrhea, abdominal pain
>100mg of iron taken orally cause acute toxicity with
presence of nausea, diarrhea and abdominal pain.
●Hemosiderosis-iron excess. (Hemosiderin)
Hemosiderinis pigment-golden brown granules in spleen
and liver.
Seen in person requiring the repeated blood transfusion
leading to iron overload. Eg. Hemophilicchild or thalassemia
etc.,

23. Toxicity :
●Bantu siderosis-seen in africans, due to corn as staple
diet.
●Cooking in iron vessels.
●Hemochromatosis: total body level higher than 25-30gm;
hemosiderindeposits in liver, leads to cell damage and liver
cirrhosis. Deposits under the skin to cause yellow-brown
discoloration
●Bronze diabetes -triad: cirrhosis + hemochromatosis+
Diabetes.

24. Treatment of hemosiderosis
●Repeated phlebotomy till serum iron and ferritin reach
normal level
●Desferroxamine–chelating agent forms iron chelate
which is excreted in urine.

25. Dr Anurag Yadav
MBBS, MD
Assistant Professor
Department of Biochemistry
Instagram page –biochem365
Email: [email protected]