Biochem Lecture 5

Question 1

How does Iron circulate in blood?

Answer 1

Bound to Transferrin (all iron)

Question 2

How is Iron stored in cells (not RBCs)?

Answer 2

Bound to Ferritin

Question 3

How is Iron bound in RBCs?

Answer 3

Bound to haemoglobin

Question 4

How much Iron circulates in plasma?

Answer 4

Very little (0.1% of total body iron) and is bound to transferrin

Question 5

Iron losses / excretion

• via which 2 systems?
• how much daily?
• which type of iron is excreted?

Answer 5

• via GIT and Skin
• about 1mg/day
• Ion-ferretin (due to desquamation of cells)
• almost all iron is recycled

Question 6

Transferrin normal rate of saturation (i.e. bound) in plasma?

Answer 6

about 1/3

Question 7

Factors that may affect plasma iron levels

Answer 7

age, sex, pregnancy, contraception, random, circadian rhythm, menstruation cycle; also, any acute or chronic illness (such as malignancy, renal disease, RA, chronic infections - often ass. w. normochromatic normocytic anaemia)

Question 8

Iron-deficiency anaemia

• appearance of cells
• stainable bone marrow iron: reduced or increased amounts?
• ferretin levels?

Answer 8

Iron-deficiency anaemia:

• hypochromatic, microcytic aneamia
• reduced amount of stainable bone marrow iron (less Iron)
• ferretin levels usually low (less iron)

Question 9

Iron overload

• causes
• plasma levels of ferretin
• stainable bone marrow iron: reduced or increased amounts?

Answer 9

Iron overload:

• diet or supplementation; idiopathic haemachromatosis (depots of excess iron in tissues); anaemia with increased but ineffective RBC synthesis
• Ferretin levels usually high (more Iron)
• stainable bone marrow iron are increased (more Iron)

Question 10

How are Iron stores assessed?

• 2 tests
• how do they change in chronic illnesses ass w low plasma iron concentration
• how do they change in nephrotic syndrome

Answer 10

Plasma transferrin
Total Iron Binding Capacity (TIBC)

• Chronic illness with low plasma iron: TIBC and Plasma Transferrin are also low
• nephrotic syndrome is also associated with low plasma iron => very low TIBC and plasma transferrin

Question 11

Inflammatory conditions and Ferritin levels

Answer 11

Ferritin is an “acute” condition protein, so any acute condition will show raised levels.

Ferretin is always HIGH with IRON OVERLOAD
(may also be due to liver disease, inflammation or tumour)

Question 12

3 Types of anaemias and causes

Other tests which help with diagnosis

Answer 12

1- iron deficiency anaemia (malabsorption, diet, bleeding, pregnancy etc):
. initially no change in RBC size
. then hypochromic, microcytic
. low plasma: ferretin, iron
. Anysocytosis (different sizes of cells)

2- macrocytic, normochromic anaemia
. Deficiencies in folic acid, vit B, or liver disease)

3- normochromic, normocytic anaemia
. Non-iron deficiency anaemia
. usually due to chronic conditions (chronic infection, inflammation, cancer, liver disease)
. normal plasma levels: iron, ferritin

Other tests:
. Blood Hb
. Plasma Transferrin
. Plasma Ferritin
. blood count (RBC, WBC, Platelets, mean cell volume, mean cell Hb, Hematocrit)

Question 13

Clotting (haemostasis)

- investigations (2)

Answer 13

• Platelet counts
  . If reduced: increased risk of bleeding
  . If increased: increased risk of thrombosis
• Prothrombin time and INR
  . Normal patient INR: 0.9 - 1.2
  . Therapeutic INR range: should be 2-3