Sarcoidosis Hypercalcaemia — FRCA Final MCQ

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HardPreoperative AssessmentSarcoidosis HypercalcaemiaFRCA Final

A 40-year-old woman with known sarcoidosis is scheduled for mediastinoscopy. Pre-operative investigations show hypercalcaemia (corrected calcium 3.2 mmol/L). What is the mechanism of hypercalcaemia in sarcoidosis?

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Correct answer: C — Granuloma-mediated 1-alpha-hydroxylase activity producing excess 1,25-dihydroxyvitamin D

Sarcoidosis causes hypercalcaemia through extra-renal production of 1,25-dihydroxyvitamin D (calcitriol) by activated macrophages within granulomas. The enzyme 1-alpha-hydroxylase, normally regulated in the kidney, is constitutively active in granulomatous tissue. This increases intestinal calcium absorption and bone resorption. Treatment: corticosteroids (which suppress granuloma activity and reduce 1-alpha-hydroxylase), hydration, and avoidance of calcium and vitamin D supplementation. Hypercalcaemia affects anaesthetic management through effects on cardiac conduction, renal function, and neuromuscular junction.

Reference: RCOA – 2023 – Preoperative assessment: endocrine disorders; BTS – 2020 – Sarcoidosis guidelines