Full blood count and blood-film interpretation in children — formative SAQs

SAQ 1 — The toddler with a low haemoglobin (10 marks, 15 minutes)

An eighteen-month-old boy is brought to the clinic with pallor noticed by his grandmother. He drinks roughly 700 millilitres of unmodified cow's milk a day and eats little else. His full blood count shows a haemoglobin of 72, a mean cell volume of 58, and a red cell distribution width that is high. The white cell count and platelet count are normal for age, and the blood film shows microcytic hypochromic red cells with no abnormal cells. ^[6]

a) State the most likely diagnosis and justify it from the age, the dietary history, the indices and the film. (2 marks) ^{[5] [6]}

b) Outline the iron studies you would request and interpret, and explain why a single ferritin can be misleading. (2 marks) ^[6]

c) Give the oral elemental iron dose, route, expected timeframe to a reticulocyte response, and the total duration of therapy. (3 marks) ^{[5] [6]}

d) Distinguish this picture from thalassaemia trait using the red cell distribution width, the red cell count and the Mentzer index, and state the confirmatory test. (3 marks) ^{[6] [7]}