Definition & Etiology

Definition

– Serum calcium > 2.6mmol/L on 2 separate occasions
– Severity classification:
– Mild: 2.6-3.0 mmol/L
– Moderate: 3.01-3.4 mmol/L
– Severe: >3.41 mmol/L

Prevalence
– 1 in 1000 individuals

Etiology
Primary causes:
– Primary hyperparathyroidism: parathyroid adenomas, hyperplasia, ectopic tissue
– Malignancy: PTH-related protein release (breast, small cell lung cancer)
– Drug-induced: lithium, vitamin D, calcium supplements, thiazide diuretics
– Granulomatous disease: TB, sarcoidosis, eosinophilic granulomas
– Renal: chronic renal failure (secondary/tertiary hyperparathyroidism)
– Familial hypercalciuric hypercalcaemia: autosomal dominant
– Non-PTH related: Addison’s, thyrotoxicosis, pheochromocytoma
– Immobility: accelerated bone turnover