- Iron is essential for hemoglobin and myoglobin and the total body iron content is around 3-5g, with most found in blood, liver, bone marrow and muscles.
- Daily iron requirements vary from 20mg for adults to 40mg for pregnant women. Absorption is regulated to maintain iron balance in the body.
- Sources of iron include leafy vegetables, pulses, cereals, liver and meat. Absorption is affected by factors like ascorbic acid and interfering substances like phytic acid.
2. DISTRIBUTION OF IRON
• Total body iron content is 3 to 5 gm, 75% of which is
present in blood. The rest is in liver, bone marrow and
muscles.
• 75% of the blood iron is hemoglobin, 5% myoglobin and
15% ferritin.
3. REQUIREMENT OF IRON
• Daily requirement for an adult Indian is 20mg of iron out
of which 1-2mg is absorbed.
• Children between 13-15 years need 20-30 mg/day.
• Pregnant women need 40 mg/day. Transfer of iron and
calcium from mother to fetus occurs mainly during last
trimester of pregnancy.
4. • During first three months of life, iron intake is negligible
and during this time child is dependent on iron reserve.
• Premature babies are at risk of iron deficiency anemia.
• After 3 months of life, diet supplementation with cereals
essential for supplying iron requirement.
5. SOURCES OF IRON
• Leafy vegetables
• Pulses
• Cereals
• Liver
• Meat
• Jaggery
6. FACTORS AFFECTING ABSORPTION OF IRON
• Reduced form of iron
• Ascorbic acid – Helps to reduce ferric ions
• Interfering substances – Phytic acid(in cereals) and
Oxalic acid(in leafy vegetables) forms insoluble salts.
• Other minerals like calcium, copper, lead and
phosphates will inhibit iron absorption.
7. MUCOSAL BLOCK THEORY
• Duodenum and jejunum are sites of absorption.
• Iron metabolism is maintained by regulation at level of
absorption and not by excretion. – One Way Element
• When iron stores in body are depleted absorption is
enhanced. Reverse when adequate quantity is present.
9. REGULATION OF ABSORPTION
• Mucosal Regulation
• Stores Regulation
• Erythropoietic regulation – erythroid cells signal
mucosa to increase absorption
10. IRON TRANSPORT
• Transport form of iron is transferrin, a beta glubulin.
Normal plasma level – 250mg/100ml. Increased in iron
deficiency.
• Total Iron Binding Capacity in plasma is 400mg/100ml,
this is provided by transferrin.
• One third of this capacity is saturated with iron, this
protein bound iron(serum iron) is about 120mg/dL.
• Ceruloplasmin is the ferroxidase which oxidises ferrous
to ferric state.
11. • Transferrin receptors are present on most body cells,
especially on cells which synthesize heme.
• Iron transferrin complex taken up by body cells by
receptor mechanism. The receptor binds 2 molecules of
transferrin and is internalized. Iron is taken up by the
cells and the receptor molecules are externalized.
• Reticulocyte can internalize 1 million atoms of iron per
minute.
12. STORAGE OF IRON
• The storage form of iron is ferritin.
• Its seen in intestinal mucosal cells, liver, spleen and
bone marrow.
• Apoferritin can take up to 4000 atoms of iron per
molecule.
13. IRON IS CONSERVED
• When RBC is lysed Hb is released into circulation.
Being low molecular weight, Hb will be lost through
urine.
• To prevent this Hb is immediately taken up by
haptoglobin an alpha globulin
• Haptoglobin is an acute phase protein and its level is
increased in inflammation
• Globin part is removed from Hb, and the heme is
released into circulation.
14. • In order to prevent excretion of haeme through urine,
heme is bound with hemopexin.
• Hemopexin is a beta globulin whose levels are
enhanced during increased haemolysis.
• Heme-hemopexin complex is taken up by hepatocytes.
• The porphyrin is removed and the free iron is either
stored or utilized.
15. EXCRETION
• Iron is a one way element. Regulation of homeostasis
is done at level of absorption.
• Almost no iron is excreted through urine. Feces
contains unabsorbed iron as well iron trapped in
intestinal cells that are desquamated.
• 30% of intestinal lining cells are replaced every day
hence this loss is considerable.
• All cells in skin contain iron. Hence iron is lost by
shedding of upper layers of skin.
16. HEMOGLOBIN
• It’s the chief respiratory pigment in humans. Each Hb
molecule consists of 4 heme residues located in globin
chains.
• Iron present in Fe 2+ state
• Normal Values:
• Male : 13 – 18 g/dL
• Female : 11.5 – 16.5 g/dL
