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

Step 1: Pull out the key clues.
The child has anaemia with a high reticulocyte count, which means the bone marrow is working hard to replace red cells, a sign of ongoing haemolysis. The peripheral smear shows target cells, cells with a bullseye look, and normoblasts, nucleated red cells released early from the marrow. The younger brother has the same illness, so the condition runs in the family.

Step 2: Match the smear findings to a diagnosis.
Target cells are the classic finding in haemoglobinopathies, especially thalassemia, and also in some abnormal haemoglobin variants like haemoglobin E disease. Normoblasts in the peripheral blood point to a marrow under stress, trying to churn out extra red cells because of chronic haemolysis.

Step 3: Use the family history.
A sibling with the identical picture supports an inherited, genetically transmitted blood disorder rather than an acquired one. Thalassemia and related haemoglobinopathies are inherited in an autosomal recessive pattern, which fits two affected siblings born to unaffected or carrier parents.

Step 4: Pick the right test.
Haemoglobin electrophoresis separates the different haemoglobin types, such as HbA, HbA2, HbF, and HbS, by their charge, and it directly shows the abnormal haemoglobin pattern seen in thalassemia and other haemoglobinopathies. This is the test that confirms the diagnosis suggested by target cells.

Step 5: Rule out the other tests.
Bone marrow biopsy is not needed here, it is reserved for cases where marrow failure or infiltration is suspected, not a straightforward haemolytic anaemia with a clear smear pattern. The osmotic fragility test diagnoses hereditary spherocytosis, which shows spherocytes on the smear, not target cells. Chromosomal analysis looks for structural or numerical chromosome problems and plays no role in diagnosing a haemoglobin disorder.

Final Answer:
Haemoglobin electrophoresis is the correct investigation to confirm a haemoglobinopathy such as thalassemia.