Hypercalcaemia in elderly hospital in-patients: value of discriminant analysis in differential diagnosis.

Plasma calcium was measured routinely as a part of profile screening of patients admitted to a geriatric department. Pathological hypercalcaemia was found in 1.33% of those screened, the cause being bone metastases (29%), hyperparathyroidism (21%), bronchial carcinoma without bone metastasis (18.5%), lymphosarcoma without bone metastasis (8%) and multiple myeloma (2.5%). There remained a further group of patients with hypercalcaemia and renal failure (21%) in whom diagnosis was often obscure. Where renal function was normal, discriminant analysis showed that the four main diagnostic groups were biochemically distinguishable. Discriminant analysis thus seems likely to be of practical value in the differential diagnosis of hypercalcaemia in elderly patients with normal renal function, but requires prospective validation.