Development of Hypercalcemia in a Patient Receiving Peginterferon alfa ‐2a Therapy for Polycythemia Vera

We describe a 25‐year‐old man with polycythemia vera who became resistant to hydroxyurea after 6 years of treatment, requiring therapeutic phlebotomy procedures with increasing frequency for elevated hemoglobin and hematocrit levels. PEG‐IFN alfa‐2a was then initiated at 90 μg subcutaneously once/week and was progressively increased to 180 μg/week over the next 11 months, with normalization of his hemoglobin and hematocrit. The patient then developed hypercalcemia with low parathyroid hormone, parathyroid hormone–related protein, and 25‐hydroxyvitamin D levels, and high 1,25‐dihydroxyvitamin D and angiotensin‐converting enzyme levels, without other evidence of sarcoidosis. PEG‐IFN alfa‐2a was discontinued, treatment with intravenous fluids and zoledronic acid was initiated, and the hypercalcemia resolved 10 weeks later. Use of the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship (score of 7) between the patient's development of hypercalcemia and PEG‐IFN alfa‐2a therapy; the relationship could not be considered as definite because the patient was not rechallenged with the drug. To our knowledge, this is the first case report of IFN‐induced hypercalcemia without other manifestations of sarcoidosis. Practitioners should be aware of hypercalcemia as a potential complication of PEG‐IFN alfa‐2a therapy, as well as its protracted time course, in patients with myeloproliferative neoplasms.
Source: Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy - Category: Drugs & Pharmacology Authors: Tags: Case Report Source Type: research