Full blood count and blood-film interpretation in children — branching viva

Opening — framing the printout

The examiner begins: here is a full blood count with a haemoglobin of 100. Before I ask you anything, what is the single most important piece of information missing, and why does it change your interpretation? ^[1]

I would say the age of the child. A haemoglobin of 100 is read against an age-specific paediatric range, and the same number is normal for a two-month-old infant at the physiological nadir of infancy and abnormal for a ten-year-old. I cannot interpret any paediatric value without the age band, and I would not apply adult ranges. ^{[1] [4]}