Endocrine late effects of cancer treatment — branching viva

Branch 1 — the brain-tumour survivor with growth failure

The candidate is expected to justify growth hormone deficiency over a normal variant from the growth velocity, the delayed bone age and the low IGF-1, and to explain that growth hormone deficiency is the earliest and most common endocrine late effect of cranial radiation because the somatotroph axis is the most radiosensitive, with a dose-dependent threshold near 18 Gy and near-universal occurrence at the 36 Gy cranial dose. The confirmation is the growth hormone stimulation test with a peak below the age-appropriate cutoff, and the imaging is the pituitary magnetic resonance imaging scan that must precede any recombinant growth hormone because growth hormone is a mitogen. ^{[1] [2]}

The examiner branches into the dose hierarchy: growth hormone deficiency at 18 Gy, gonadotropin disturbance at 24 to 30 Gy, TSH and ACTH deficiency above 30 to 40 Gy, and panhypopituitarism at the highest doses — so this survivor must be screened across the whole axis, not only for growth hormone deficiency. The replacement order is named and justified: hydrocortisone before levothyroxine before sex steroids, with recombinant growth hormone after the magnetic resonance imaging, because giving thyroxine before cortisol precipitates an adrenal crisis. ^{[2] [6]}