Hypopituitarism and pituitary lesions — branching viva

A falling height velocity with downward percentile crossing points to an acquired or progressive pathology rather than a normal variant. Constitutional delay and familial short stature both grow steadily, with a normal velocity for bone age, so a child who is decelerating has a hormone deficiency or a lesion until proven otherwise. The next steps are IGF-1, a bone age, paired pituitary and target hormones, and MRI if any neurological clue is present. [7]

Growth hormone is secreted in pulses, so a random level drawn between pulses is low in healthy children and cannot diagnose deficiency. Confirmation needs a growth hormone stimulation test — an insulin tolerance test, or glucagon, arginine or clonidine stimulation — showing a subnormal peak, interpreted together with a low IGF-1 and clinical growth failure. [7]

Anterior hormones tend to fail in a predictable order — growth hormone first, then gonadotrophins, then thyroid-stimulating hormone, then adrenocorticotrophin — and deficiencies can accumulate over time. Cortisol deficiency is last to appear but the most dangerous, because it causes hypoglycaemia and adrenal crisis. Every axis is screened, and central hypothyroidism is caught only by measuring the free thyroxine, which is low with a low or normal thyroid-stimulating hormone. [1]

A thickened stalk with central diabetes insipidus and new anterior deficiency is an intracranial germinoma until proven otherwise. Send serum and cerebrospinal-fluid beta-human-chorionic-gonadotrophin and alpha-fetoprotein, and involve neurosurgery and oncology. Germinoma is highly radiosensitive and chemosensitive, so early diagnosis carries an excellent prognosis, which is why watching a thickened stalk without markers is unsafe. [6]

Glucocorticoid is always started before levothyroxine. Thyroxine raises the metabolic rate and accelerates cortisol clearance, so starting it first in a child with marginal cortisol reserve can precipitate an adrenal crisis. Give hydrocortisone first with sick-day and stress dosing, then add levothyroxine, then growth hormone once cortisol cover is secure, then sex steroids at the appropriate age. [10]

The triad of neonatal hypoglycaemia, prolonged jaundice and a micropenis is congenital hypopituitarism with central adrenal insufficiency until proven otherwise. Draw a critical sample for paired glucose, cortisol, growth hormone and free thyroxine, then treat the hypoglycaemia with glucose and give stress-dose hydrocortisone without waiting for results. [11]