SU22.5-6 | Parathyroid Anatomy and Parathyroid Disorders — Summary & Reflection

KEY TAKEAWAYS

The parathyroid glands — usually four, each a few millimetres across, lying on the posterior thyroid, derived from the third (inferior) and fourth (superior) pharyngeal pouches and supplied by the inferior thyroid artery — control serum calcium through PTH, which raises calcium via bone, kidney and vitamin-D-mediated gut absorption (SU22.5). Their disease presents through the calcium rather than as a neck lump (SU22.6). Hyperparathyroidism is classified as primary (autonomous PTH excess, adenoma in ~85%, giving high calcium with high/inappropriately normal PTH), secondary (compensatory PTH rise to the hypocalcaemia of CKD or vitamin D deficiency, with low/normal calcium) and tertiary (autonomous secretion after long-standing secondary disease, with high calcium); its features follow the high calcium — 'stones, bones, abdominal groans and psychiatric moans'. Hypoparathyroidism, usually iatrogenic after neck surgery, causes hypocalcaemia with paraesthesiae and the Chvostek and Trousseau signs. Diagnosis is biochemical (calcium, PTH, phosphate); primary disease is then localised by ultrasound and sestamibi and cured by parathyroidectomy (focused or bilateral exploration), secondary disease is managed medically, and hypocalcaemia is treated with calcium and active vitamin D.

REFLECT

Return to the woman in the opening scenario with stones, bone aches, constipation and low mood whose calcium turned out to be high. Trace how a single overactive gland could produce that scattered picture, and ask yourself what one pair of blood tests would confirm the diagnosis before any scan is ordered. Then consider the mirror image: a patient who develops tingling fingers the night after a thyroidectomy. Reflecting on how the same small glands cause opposite syndromes — and how the anatomy you learned for thyroid surgery explains the post-operative one — is what turns isolated facts into reliable bedside judgement.