Short stature and poor linear growth — viva

Stem

You are the paediatric registrar in clinic. The examiner asks you to assess a child whose growth chart shows the height centile falling, and to defend your plan. [2]

Branch A — Opening interpretation

Examiner: What is the single most important feature on this chart? [2]

Strong answer: The downward centile crossing. A single low point defines short stature but does not diagnose disease. Velocity does: a child whose height centile is falling has growth failure and needs a work-up, whereas a child tracking a low parallel channel is usually a variant. So I re-measure to confirm the chart is real, then interpret the velocity. [2] [4]

Branch B — Body proportion

Examiner: The child looks a little short-limbed. What do you do? [6]

Strong answer: I measure the upper-to-lower segment ratio and the arm-span-to-height difference at the bedside. A ratio wrong for age, or an arm span that differs from height by more than about 5 cm, flags disproportionate short stature and points me toward a skeletal dysplasia or SHOX haploinsufficiency. Disproportion changes the differential immediately and I arrange imaging and genetics rather than an endocrine panel alone. [2] [6]

Branch C — Endocrine pattern

Examiner: Weight is rising while height falls. What does that tell you? [4]

Strong answer: Weight rising with poor linear growth is a classic endocrine pattern. Acute energy deficit drops weight before height; chronic endocrine disease — hypothyroidism, growth-hormone deficiency, Cushing syndrome or glucocorticoid exposure — slows height while weight is preserved or up. So I check thyroid function and the growth-hormone axis first, and I examine for goitre, striae and a Cushingoid habitus. [2] [4]

Branch D — Investigation and GH testing

Examiner: When do you stimulate-test for growth hormone? [3]

Strong answer: Only after the first-line panel and the pre-test probability point to deficiency. Random growth-hormone levels are pulsatile and unhelpful, so I screen with IGF-1 and IGFBP-3 first. Stimulation testing belongs with paediatric endocrinology, reserved for a child with poor velocity, low IGF-1, and a plausible endocrine cause, using pharmacological stimuli after priming where local protocols require. Cranial imaging follows if a central cause is confirmed or suspected. [3] [4]

Branch E — SGA without catch-up

Examiner: She was born small for gestational age and never caught up. [5]

Strong answer: SGA is a birth-size label and fetal growth restriction is a fetal process; the two are not identical. Many SGA infants catch up by two to four years. Those who do not are a defined group for whom growth hormone is licensed under international consensus criteria, alongside surveillance for later metabolic risk. I confirm the birth-size history, plot the catch-up trajectory, and refer to endocrinology if she meets the criteria. [5]

Branch F — Management and traps

Examiner: The parents want growth hormone to make her taller. [1]

Strong answer: I would not prescribe growth hormone for a child outside a licensed indication. Growth hormone is a daily subcutaneous injection at about 0.18 to 0.30 mg/kg/week, licensed for growth-hormone deficiency, Turner, Prader-Willi, SGA without catch-up, SHOX deficiency, chronic kidney disease–related growth failure in some jurisdictions, and idiopathic short stature meeting strict criteria. For idiopathic short stature the benefit is modest and shared decision-making is essential. If she is a variant, I reassure, follow, and do not medicalise healthy shortness. [1] [3]

Examiner traps

• Diagnosing disease from one low point without velocity.
• Missing disproportion by not measuring the segment ratio or arm span.
• Over-investigating a familial variant, or under-investigating a falling centile in a well-looking child.
• Prescribing growth hormone outside licensed indications.
• Missing safeguarding in psychosocial short stature. [1] [2] [4]