Macrocytosis Without Megaloblastic Changes

Question 1

What does macrocytic anaemia refer to?

Answer 1

Anaemia with red blood cells that have a larger-than-normal volume (high MCV)

Question 2

What are causes of non-megaloblastic macrocytosis?

Answer 2

(1) Alcohol (may not be associated with anaemia)

(2) Liver disease (may not be associated with anaemia)

(3) Hypothyroidism (may not be associated with anaemia)

(4) Marrow failure (associated with anaemia)

Question 3

What is spurious macrocytosis and how is it caused?

Answer 3

Spurious macrocytosis occurs when the volume of mature red cells is normal but MCV appears high, often due to reticulocytosis or cold agglutinin

Question 4

How does reticulocytosis cause spurious macrocytosis?

Answer 4

Reticulocytes are larger than mature red blood cells and can increase MCV measurement when present in high numbers

Question 5

What should be done if cold agglutinins are suspected in a macrocytic blood sample?

Answer 5

Ensure the sample is warmed to 37°C to avoid RBC clumping and obtain an accurate MCV