Lecture 3: Microcytic & Macrocytic Anaemia

Question 1

Define anaemia based on Hb levels.

Answer 1

Hb below normal range for age/sex (Male: 13.3–16.7 g/dL; Female: 11.8–14.8 g/dL).

Question 2

What distinguishes microcytic from macrocytic anaemia?

Answer 2

Microcytic: MCV < 80 fL (e.g., iron deficiency, thalassemia).

Macrocytic: MCV > 98 fL (e.g., B12/folate deficiency).

Question 3

Name 3 causes of microcytic anaemia.

Answer 3

Iron deficiency, chronic disease, thalassemia.

Question 4

Key blood film findings in iron deficiency anaemia (IDA)?

Answer 4

Microcytosis, hypochromia, poikilocytosis, anisocytosis.

Question 5

Why is serum ferritin misleading in inflammation?

Answer 5

It’s an acute-phase protein (falsely normal/elevated despite iron deficiency).

Question 6

What causes megaloblastic macrocytic anaemia?

Answer 6

Impaired DNA synthesis (B12/folate deficiency → ↑ dUMP/dTMP imbalance).

Question 7

How does B12 absorption work?

Answer 7

B12 binds intrinsic factor (IF) → absorbed in ileum via cubilin/megalin receptors.

Question 8

Why do alcoholics risk folate deficiency?

Answer 8

Poor diet + folate heat-labile; alcohol inhibits absorption/metabolism.

Question 9

What is the autoimmune target in pernicious anaemia?

Answer 9

Gastric parietal cells → no intrinsic factor → B12 malabsorption.

Question 10

Treatment for B12 deficiency due to pernicious anaemia?

Answer 10

Lifelong B12 injections (oral absorption ineffective without IF).

Question 11

What FBC indices suggest thalassemia vs. IDA?

Answer 11

Thalassemia: ↓ MCV, ↑ RBC count; IDA: ↓ MCV, ↓ RBC count.

Question 12

Why is homocysteine elevated in B12/folate deficiency?

Answer 12

Both are cofactors in homocysteine → methionine conversion.