Question

A 5 year old child has anaemia with an increased reticulocyte count. The peripheral smear shows target cells and normoblasts. The patient's younger brother suffers from the same condition. What investigation should be performed?

• A. Hb electrophoresis
• B. Bone marrow biopsy
• C. Osmotic fragility test
• D. Chromosomal analysis

Hint:

Target cells plus a family history point to a haemoglobinopathy; Hb electrophoresis confirms it.

Answer 1

The Correct Option is A

This question is testing which test confirms a suspected inherited haemoglobin disorder in a child with a haemolytic anaemia picture.

1. Hb electrophoresis: separates the different types of haemoglobin present in the blood, and it is the direct way to detect an abnormal or reduced haemoglobin type, exactly what target cells and a family history of the same illness point towards.
2. Bone marrow biopsy: is used when the marrow itself may be failing or infiltrated, such as in aplastic anaemia or leukaemia, not for a child who already has a raised reticulocyte count showing the marrow is working well.
3. Osmotic fragility test: checks how easily red cells burst in a dilute salt solution, and it is the test of choice for hereditary spherocytosis, where the smear shows spherocytes, not the target cells described here.
4. Chromosomal analysis: looks for extra, missing, or rearranged chromosomes, useful in syndromes like Down syndrome, but haemoglobin disorders are gene-level problems that this test cannot pick up.

Given the target cells, the high reticulocyte count, and an affected sibling, the picture fits an inherited haemoglobinopathy, and haemoglobin electrophoresis is the test that will show the abnormal haemoglobin pattern.

Let's summarize:

• Target cells point toward a haemoglobinopathy like thalassemia, not spherocytosis.
• Hb electrophoresis, not osmotic fragility or chromosome studies, confirms this kind of disorder.

So the investigation to perform is haemoglobin electrophoresis.