is caused by uncontrolled parathyroid hormone produced directly by a tumour of the parathyroid glands. Most cases due to solitary adenoma (80%), multifocal disease occurs in 10-15% and parathyroid carcinoma in 1% or less

This leads hypercalcaemia: an abnormally high level of calcium in the blood. This is treated by surgically removing the tumour.

In exams, primary hyperparathyroidism is stereotypically seen in elderly females with an unquenchable thirst and an inappropriately normal or raised parathyroid hormone level. It is most commonly due to a solitary adenoma

Causes of primary hyperparathyroidism

• 80%: solitary adenoma
• 15%: hyperplasia
• 4%: multiple adenoma
• 1%: carcinoma

Associations

• hypertension
• multiple endocrine neoplasia: MEN I and II

PC

Around 80% of patients are asymptomatic and are diagnosed on routine blood tests. The symptomatic features of primary hyperparathyroidism may be remembered by the mnemonic: 'bones, stones, abdominal groans and psychic moans':

• polydipsia, polyuria
• depression
• anorexia, nausea, constipation
• peptic ulceration