Phaeochromocytoma and endocrine hypertension — branching viva

The diagnosis is a catecholamine-secreting tumour (phaeochromocytoma or paraganglioma). The first test is plasma free metanephrines or a twenty-four-hour urine fractionated metanephrines collection. The tumour cell continually converts catecholamines to metanephrines that leak into plasma continuously, whereas catecholamine release is episodic from stored vesicles — so a random catecholamine level drawn between spells reads normal and misses the tumour, while metanephrines do not. [3]

Every child with a phaeochromocytoma or paraganglioma earns a hereditary gene panel, because around forty percent carry a pathogenic germline mutation — far above adults. The panel covers the SDHx cluster, VHL, RET, NF1, TMEM127, MAX and FH. An SDHB mutation is the one that concerns the examiner most, because it marks extra-adrenal paraganglioma with real metastatic potential, converting the child onto a lifelong malignancy-surveillance pathway. [7]

Say no — beta-blockade must never precede alpha-blockade. Start phenoxybenzamine at around 0.5 mg per kilogram per day and titrate over ten to fourteen days to the block-and-fill end-point, then add a beta-blocker only once the child is fully alpha-blocked. Giving a beta-blocker first removes beta-two vasodilator tone and leaves unopposed alpha-one vasoconstriction, precipitating a hypertensive crisis that can be fatal. [1]

Stop the biopsy. An adrenal mass in a child is a phaeochromocytoma until the metanephrines come back normal, and biopsying a catecholamine tumour that has not been alpha-blocked can release a lethal catecholamine surge. The rule is biochemistry first, imaging second, biopsy never — and only after the tumour is fully blocked should it even be handled in theatre. [1]

This is a monogenic mineralocorticoid cause of low-renin, low-aldosterone hypertension — most likely Liddle syndrome. The rational first drug is amiloride, which blocks the epithelial sodium channel directly. Spironolactone is the wrong choice because it blocks the mineralocorticoid receptor, and in Liddle syndrome the receptor is not the problem — the channel is constitutively open from the gain-of-function mutation, so spironolactone under-controls the blood pressure. [11]

Endocrine hypertension splits into catecholamine-mediated disease (phaeochromocytoma and paraganglioma), caught by metanephrines and fixed by alpha-blockade then surgery, and mineralocorticoid-mediated disease, caught by the renin–aldosterone–potassium panel and fixed by matching the drug to the gene. Phaeochromocytoma sits apart because it is catecholamine-mediated and does not fit the renin–aldosterone axes. [12]