Iron (The First Micromineral)

Question 1

What are microminerals?

Answer 1

The daily requirement is <100 mg
Ten trace elements: Fe, I, Cu, Mn, Zn, Mo, Co, F, Se, Cr

Question 2

In what form is iron absorbed?

Answer 2

Ferrous (2+) form

Question 3

In what form is iron transported?

Answer 3

Ferric (3+) form

Question 4

What are the six compartments into which iron is distributed?

Answer 4

1. Hemoglobin (contains 70% (2-2.5g) of the body iron)
2. Storage proteins - Ferritin & hemosiderin (contains 20% (0.6-1.0 g iron))
3. Myoglobin (contains 5% or 0.13 g iron)
4. Labile Pool - Iron bound to membranes or cytoplasmic proteins (contains 0.08-0.09g)
5. Transport iron bound to:
   Transferrin c.250 mg/dL in the body (contains 400µg of iron/dL plasma)
   Plasma ferritin c.10µg/dL (contains 5-7% iron)
6. Tissue iron in bone marrow, liver and reticuloendothelial system (0.006 to 0.008 gm iron)

Question 5

Forms of tissue iron

Answer 5

Heme proteins: Cytochromes, Peroxidases, Catalase, Tryptophan pyrrolase
Flavoproteins: Xanthine oxidase, Dehydrogenases, Cytochrome C reductase
Iron–sulphur complexes: Adrenodoxin, Complex III Fe-S
Other non-heme proteins: Aconitase, Phenylalanine hydroxylase

Question 6

What are the biochemical functions of iron?

Answer 6

Transport of oxygen and carbon dioxide
Storage of oxygen
Electron transport and oxidative phosphorylation
Immune function
Phagocytosis

Question 7

Daily iron consumption in a balanced diet

Answer 7

10-20 mg

Question 8

Amount of iron that is absorbed

Answer 8

1 mg

Amount absorbed depends on the body’s needs

Question 9

What are the sources of iron?

Answer 9

Rich sources - Organ meats, such as liver, heart and kidney
Good sources - Leafy vegetables, pulses, cereals, fish, apples and dried fruits
Poor sources - Milk, wheat, polished rice

Question 10

Which form of iron can most easily be absorbed?

Answer 10

Ferrous

Question 11

Do males or females have higher iron requirements?

Answer 11

Women have a higher iron requirement

Iron requirement increases further during pregnancy and lactation

Question 12

What factors increase the intestinal absorption of iron?

Answer 12

Acidic pH in stomach, dietary vitamin C

Question 13

What factors decrease the intestinal absorption of iron?

Answer 13

Presence of oxalates, phosphates, phytates in food (so tea & leafy vegetables decrease absorption)

Question 14

How much iron is lost per day?

Answer 14

Typical adults = 1 mg in shed epidermal and GI cells
Menstruating females lose an additional 0.5 to 1 mg/day from menses

There is no physiological mechanism to remove iron

Question 15

How may excess iron overload occur?

Answer 15

Overconsumption and excess absorption of iron
Through repeated transfusion

Question 16

What are the disorders of iron metabolism?

Answer 16

Iron deficiency anemia
Hemosiderosis
Hemochromatosis

Question 17

What type of anemia is caused by iron deficiency?

Answer 17

Hypochromic, microcytic anemia

Question 18

What is hemosiderosis?

Answer 18

Excessive iron is deposited as ferritin and hemosiderin in tissues (deposition of iron that does not cause tissue damage)

Question 19

When may hemosiderosis occur?

Answer 19

In patients receiving repeated blood transfusions
In tribes with habit of cooking food in iron pots

Question 20

What is hemochromatosis?

Answer 20

Iron is directly deposited in the tissues and cause damage (liver, spleen, pancreas and skin, endocrine glands)
Causes bronzed-pigmentation of skin, cirrhosis of liver and pancreatic fibrosis

Hemosiderosis is sometimes accompanied by hemochromatosis