Primary hyperparathyroidism — SCE Rheumatology MCQ

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EasyMetabolic bone diseasePrimary hyperparathyroidismSCE Rheumatology

A 61-year-old woman has recurrent renal stones and generalised bone pain. Her albumin-adjusted serum calcium is 2.92 mmol/L on two separate measurements. Concurrent investigations show a low serum phosphate concentration and a parathyroid hormone concentration above the reference range. What is the most likely diagnosis?

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Correct answer: E — Primary hyperparathyroidism

The correct answer is primary hyperparathyroidism. Persistent hypercalcaemia accompanied by an elevated or inappropriately non-suppressed PTH is the defining biochemical pattern. PTH also promotes renal phosphate loss, explaining the low phosphate, while recurrent renal stones and skeletal pain are recognised target-organ manifestations. Malignancy-associated hypercalcaemia usually suppresses endogenous PTH. Vitamin D deficiency may cause secondary hyperparathyroidism, but calcium is usually low or normal rather than markedly elevated. Paget disease may cause bone pain and raised alkaline phosphatase but does not ordinarily produce this calcium–PTH pattern. Postmenopausal osteoporosis likewise does not explain hypercalcaemia, hypophosphataemia or raised PTH.

Reference: National Institute for Health and Care Excellence. NG132: Hyperparathyroidism (primary): diagnosis, assessment and initial management, recommendations 1.1.1 and 1.1.5–1.1.10. 2019. https://www.nice.org.uk/guidance/ng132/chapter/Recommendations