Endocrine Surgery
Endocrine questions test biochemical diagnosis, localisation and the prevention of perioperative catastrophe. The thyroid, parathyroid and adrenal glands each have a classic emergency that must be recognised instantly.
Thyroid
- Nodule assessment is clinical, ultrasound and cytology; the Bethesda system grades cytology I–VI, with categories V and VI going to surgery.
- Papillary carcinoma spreads via lymphatics; psammoma bodies and Orphan Annie nuclei. Follicular carcinoma spreads haematogenously and needs capsular or vascular invasion for diagnosis. Medullary carcinoma secretes calcitonin and is linked to RET mutations and MEN2.
- Risks of thyroidectomy: recurrent laryngeal nerve injury (hoarseness), external branch of superior laryngeal nerve injury (voice fatigue, pitch loss), hypocalcaemia from parathyroid devascularisation, haematoma.
- Postoperative haematoma with stridor is an airway emergency: open the wound at the bedside, evacuate the clot, then take the patient to theatre.
- Hypocalcaemia appears at 24–72 hours: perioral tingling, Chvostek and Trousseau signs; treat with calcium gluconate and oral calcium with alfacalcidol.
Parathyroid
- Primary hyperparathyroidism: high calcium, low phosphate, inappropriately high PTH, raised urinary calcium. Secondary hyperparathyroidism from renal failure has high phosphate.
- Localisation by ultrasound and sestamibi; intraoperative PTH that falls by more than 50% ten minutes after excision indicates cure.
- Hungry bone syndrome causes prolonged hypocalcaemia after parathyroidectomy in severe disease.
Adrenal
- Phaeochromocytoma: paroxysmal hypertension, headache, sweating, palpitations; diagnose with plasma metanephrines. Prepare with alpha blockade (phenoxybenzamine) for 10–14 days before adding a beta blocker - never beta first.
- Conn syndrome: hypertension, hypokalaemia, high aldosterone with suppressed renin.
- Cushing syndrome: dexamethasone suppression tests; adrenal incidentalomas larger than 4 cm or with malignant features are excised.
- Patients on long-term steroids need perioperative hydrocortisone cover (for example 100 mg at induction, then tapering).
Neuroendocrine tumours
- Carcinoid: serotonin, chromogranin A, urinary 5-HIAA; octreotide controls carcinoid crisis.
- MEN1: parathyroid, pituitary and pancreatic tumours. MEN2A: medullary thyroid cancer, phaeochromocytoma, parathyroid hyperplasia. MEN2B adds mucosal neuromas and marfanoid habitus.
Worked example
A patient develops stridor two hours after total thyroidectomy. The cause is a compressive haematoma, not recurrent laryngeal nerve palsy or hypocalcaemia. Open the skin and deep sutures at the bedside, evacuate the clot, secure the airway, then return to theatre for haemostasis.
Traps that lose marks
Giving a beta blocker before alpha blockade in phaeochromocytoma; failing to check calcium after total thyroidectomy; misinterpreting a normal PTH as excluding primary hyperparathyroidism; ignoring a family history that suggests MEN2.