Multiple myeloma presenting with recurrent hypercalcemia in a patient with a history of primary hyperparathyroidism: report of case and review of literature.

OBJECTIVE: To report a case of primary hyperparathyroidism (PHPT) that presented with recurrent hypercalcemia due to multiple myeloma after successful parathyroidectomy.
METHODS: The initial manifestations, investigations, and postoperative follow-up of a case of hypercalcemia due to PHPT are described. The studies performed for evaluation for recurrent hypercalcemia and the subsequent diagnosis of multiple myeloma are discussed. The association between these disorders and reports of similar cases in the literature are reviewed.
RESULTS: A 72-year-old woman was referred for incidentally discovered hypercalcemia. She had no history of kidney stones or fractures. Further investigations revealed a high parathyroid hormone (PTH) level, hypercalciuria, and low bone mass, particularly at the cortical sites. Parathyroidectomy was performed, and a right inferior parathyroid adenoma was removed. Postoperatively, both the calcium and PTH levels normalized. She presented 9 months later with a 3-week history of pain in her left hip, polyuria, nausea, and vomiting. The patient had severe hypercalcemia and a suppressed PTH level. Further investigations revealed multiple bony lytic lesions, abnormalities on serum protein electrophoresis, and features consistent with multiple myeloma on a bone marrow biopsy specimen.
CONCLUSION: Hypercalcemia can occur in patients with PHPT and multiple myeloma; however, the occurrence of both disorders in the same patient is rare. Review of the literature revealed only a few cases similar to ours. Evidence in the literature suggests that monoclonal gammopathies occur more often in patients with PHPT than in the general population; therefore, screening for monoclonal gammopathy may be warranted in patients with PHPT.