Normal growth from fetal life through adolescence — formative SAQs

SAQ 1 (10)

A 7-year-old boy is referred because he is “the smallest in his class.” Height is on the 3rd centile. Weight is on the 10th. He tracks parallel to the 3rd height centile over 18 months. Both parents are short. Examination is normal. Puberty has not begun. ^[6]

1. Outline the infancy–childhood–puberty model of linear growth and state which phase dominates at age 7. (3) ^[3]
2. List four features that support familial short stature rather than pathological short stature. (4) ^[6]
3. State when idiopathic short stature is an appropriate residual label. (3) ^[5]

Model answer

ICP at age 7. Infancy growth is largely nutrition-driven; childhood growth depends on the GH–IGF-1 axis; puberty adds sex-steroid drive and a spurt. At age 7, childhood-phase GH–IGF-1 biology dominates. ^[3]

Familial short stature features. Short parents / mid-parental height consistent with current channel; normal growth velocity (parallel tracking); normal examination without disproportion or dysmorphism; delayed evaluation not forced by red flags (systemic symptoms, falling height velocity). Bone age often near chronological age in classic familial short stature teaching, in contrast to constitutional delay. ^[6]

ISS. Idiopathic short stature is residual after complete evaluation for short stature, including exclusion of alternative causes and stimulated GH testing in consensus frameworks — not a first-glance clinic label for every child near the 3rd centile. ^[5]