Hypoparathyroidism during alpha-INF therapy in a patient with multiple myeloma.

A 66 year-old woman with multiple myeloma developed hypoparathyroidism during combination chemotherapy with melphalan, prednisolone, and alpha-interferon (INF). Seven weeks after commencement of the therapy, the serum calcium (Ca) level decreased to 7.4 mg/dL, and the phosphorus (P) level increased to 7.2 mg/dL; parathyroid hormone (PTH) was at a critically low level. By 13 weeks after discontinuation of alpha-INF, the levels of Ca, P, and PTH had returned to normal values: 8.6 mg/dL, 4.5 mg/dL, and 310 pg/ml, respectively. These changes suggest a strong correlation between hypoparathyroidism and the administration of alpha-INF. Autoantibodies against the parathyroid gland cell were not present in the serum of this patient by indirect immunofluorescent techniques. The mechanism of hypoparathyroidism by alpha-INF could not be identified, but this is the first case of this condition during alpha-INF therapy.