Iron Metabolism & Disorders Flashcards
Total body iron in the body
4g
Distribution of iron in the body (in mg)
- 2500 mg in the RBCs
- 500 mg in macrophages
- 500 mg in liver
- 500 mg in muscle
- Total 4000mg = 4g
- 4mg iron circulates in the plasma (= 0.1% of total body iron)
(all the values are approximate)
Distribution of iron in the body (in percentage)
- 70% = Haemoglobin (the majority)
- 25% = Ferritin and hemosiderin
- 4% = Myoglobin
- 0.1% = Plasma iron
Site of absorption
upper small intestine
Amount of absorption
About 10-15% of dietary iron is absorbed (regulated according to body’s need)
From intake of 6mg (per 1000Kcal) of dietary iron >>>> 15% is bioavailable
Chemical form of iron absorption
Fe2+ form from the gut
Fe2+ (ferrous) (present in gut) >>>> much better absorbed >>>> than Fe3+ (ferric) (present in blood)
Iron absorption is increased by-?
- Vitamin-C
- Gastric acid
Iron absorption in reduced by-?
- PPIs (Reduced HCL)
- Gastric achlorhydria (NO HCL)
- Tannin (in tea)
- Tetracycline
Transport of iron
From the gut >> Fe2+ enters the intestinal wall cell >>> In the intestinal wall, Fe2+ (ferrous) >> oxidation (by caeruloplasmin) >> Fe3+ (Ferric) >> enters blood >>> Fe3+ binds to transferrin >> transported throughout the body
Storage of iron
- In tissues, as ‘Ferittin’
It is a plasma protein
It is an acute phase reactant >> increased in inflammations & post-surgery
Excretion of iron
Iron (heme) of RBC >>> metabolised & re-utilised
Others >>> lost via intestinal tract (by intestinal wall desquamation) >>> 1mg/day is lost
What is Ferritin?
A plasma protein
What situations increase ferritin?
- Inflammation
- Infection
- Malignancy
Anaemias with low MCV
- IDA
- Thalassemia
- Chronic haemolytic anaemia
- Sideroblastic anaemia
- Anaemia due to chronic disease
- Haemochromatosis
- Pregnancy
Iron profile of IDA
- Serum iron: Low
- Serum ferritin: Low
- TIBC: High
Iron profile of thalassaemia
- Serum iron: high
- Serum ferritin: high
- TIBC: Low
Iron profile of chronic haemolysis
- Serum iron: high
- Serum ferritin: high
- TIBC: Low
Iron profile of sideroblastic anaemia
- Serum iron: High
- Serum ferritin: High
- TIBC: Normal (Sometimes low)
Iron profile of anaemia due to chronic diseases
- Serum iron: Low
- Serum ferritin: High
- TIBC: Low
Iron profile of haemochromatosis
- Serum iron: High
- Serum Ferritin: High
- TIBC: Low
Similarities of iron profile in thalassaemia, chronic haemolysis and haemachromatosis
- Serum iron: High
- Serum ferritin: High
- TIBC: Low
Structure of transferrin
Glycoprotein (Glucose + Protein)
Function of transferrin
carries ferric iron & helps in internal iron exchange
Transferrin level is increased by-?
IDA
Pregnancy
COCP
Transferrin level is reduced by-?
Haemochromatosis
How to calculate transferrin saturation in percentage?
(Plasma iron / TIBC) x 100
Normal transferrin saturation
33%
In absence of anaemia, 33% of transferrin remains saturated
Use of transferrin saturation
to measure iron stores
Transferrin saturation in iron deficiency
Below 16%
Relation between iron and transferrin level
Inversely proprotional
More iron >>>>> Low transferrin level
Less iron >>>>> More transferrin level
Relation between iron and transferrin saturation
Proportional
More iron >>>>> More transferrin
Less iron >>>>> Less transferrin
Conditions with high transferrin level
Iron deficiency anaemia
Pregnancy
COCP
Conditions with low transferrin level
Haemochromatosis
Conditions with high transferrin saturation
Haemochromatosis
Conditions with low transferrin saturation
Iron deficiency anaemia (below 16%)
Findings in haemochromatosis
Mucosal cells >>>>> high content + high iron saturation
Blood >>>>> Low transferrin level + High transferrin saturation
