Constitutional delay and familial short stature — formative SAQs

SAQ 1 (10)

A seven-year-old boy is referred because he is the shortest in his class. Both parents are short (father 162 cm, mother 150 cm). His birth weight was 3.1 kg at term. His height tracks just below the third centile and has done so since toddlerhood, with a normal growth velocity. His bone age equals his chronological age. ^{[1] [2]}

a) Define short stature and calculate this child's approximate mid-parental (target) height range. State the diagnosis you favour and the single investigation that confirms it. (3 marks) ^[1]

b) Explain why the bone age is the discriminator between familial short stature and constitutional delay of growth and puberty, and state the expected bone age in each. (3 marks) ^[2]

c) Name the focused blood panel you would send to exclude the pathological mimics, and give one reason for each test. (3 marks) ^[1]

d) Explain why growth hormone is not indicated for this child, and state the principle that governs its use in the normal variants. (1 mark) ^[2]