Coexistent multiple myeloma and primary hyperparathyroidism.

A patient with multiple myeloma and hypercalcemia responded to cytotoxic chemotherapy. However, hypercalcemia persisted. Because of the absence of lytic bone lesions, the presence of a low serum phosphate level, and a family history of possible primary hyperparathyroidism, the patient was evaluated for this disorder. Serum parathyroid hormone and urinary cyclic adenosine monophosphate levels were elevated. Exploration of the neck disclosed two enlarged parathyroid glands (1,850 mg and 210 mg), which were excised. After surgery, the patient's serum calcium levels remained normal for one year. Progressive myeloma bone disease developed that eventually resulted in recurrent hypercalcemia and death. Autopsy revealed only evidence of myeloma.