Causes

• primary hyperparathyroidism
• malignancy
• renal failure

• sarcoidosis
• thyrotoxicosis
• excessive vitamin D therapy

Primary hyperparathyroidism is the commonest cause in out-patients

Hospital out-patients	% (95% CI)
primary hyperparathyroidism c	54% (47% to 60%)
malignancy	35% (28% to 41%)
unknown	9.2% (5.2% to 13%)
sarcoidosis	1.0% (0.0% to 2.3%)
thyrotoxicosis	0.5% (0.0% to 1.4%)
immobilisation	0.5% (0.0% to 1.4%)
vitamin D intoxication	0.5% (0.0% to 1.4%)

Malignancy is the commonest cause in in-patients

Hospital in-patients	% (95% CI)
malignancy c	47% (42% to 51%)
no cause found	22% (18% to 26%)
on renal dialysis	15% (11% to 18%)
primary hyperparathyroidism	13% (9.6% to 16%)
excessive vitamin D therapy	2.1% (0.8% to 3.4%)
other causes	1.3% (0.3% to 2.3%)
thyrotoxicosis	0.9% (0.0% to 1.7%)
sarcoidosis	0.2% (0.0% to 0.6%)