Hypercalcemia of immobilization in an adult patient with peripheral neuropathy

A 48-year-old man developed a marked and persistent hypercalcemia 3 months after admission for paraplegia resulting from severe peripheral neuropathy most likely of alcoholic etiology. Serum ionized calcium was elevated, and parathyroid hormone levels were low normal by the two separate radioimmunoassays. Urinary calcium excretion was markedly elevated, and serum 1,25-dihydroxyvitamin D level was decreased. An extensive clinical evaluation for possible occult malignancy, myeloma, and sarcoidosis as a cause of hypercalcemia produced no positive findings. Treatment with calcitonin caused prompt normalization of serum calcium, and its discontinuation resulted in recurrence of hypercalcemia. With improvement of neuropathy, the patient started active physical therapy. We gradually discontinued calcitonin, and the patient's serum calcium remained normal during the following 11 months. We discuss difficulties in both clinical and laboratory diagnosis of hypercalcemia of immobilization in the adult patient because no specific laboratory test is available.