[Hypercalcemia in coexistent parathyroid adenoma and multiple myeloma. Problems of differential diagnosis]

In a chance observation, a 74-year-old woman was found to have hypercalcaemia (3.0 mmol/l) and multiple skeletal osteolyses. A diagnosis of multiple myeloma was made after the demonstration of paraproteins in serum (IgG-kappa) and a 10% proportion of plasma cells in a pelvic crest biopsy. Oral chemotherapy with melphalan and prednisone failed to alter the calcium level. Simultaneous increase in alkaline phosphatase and reduction in serum phosphate concentration led to further tests: determination of peripheral venous parathormone concentration, ultrasound examination of the neck, thallium-technetium subtraction scintigraphy and selective venous parathormone measurements. The results demonstrated the coexistence of primary hyperparathyroidism. The calcium level became normal after surgical removal of a parathyroid adenoma.