Lenalidomide-induced refractory hypocalcemia in a patient with chronic kidney disease and multiple myeloma: case report and review of the literature

Lenalidomide is an immunomodulatory medication widely used in the treatment of multiple myeloma. However, hypocalcemia associated with lenalidomide is a little-known side effect. We report on a 52-year-old woman with stage G4 - 5 chronic kidney disease (CKD) secondary to multiple myeloma who developed lenalidomide-induced symptomatic hypocalcemia. Her serum calcium (Ca) was 8.6 mg/dL before treatment. After a month on lenalidomide, the patient developed refractory symptomatic hypocalcemia (Ca 6.3 - 7.6 mg/dL). Despite oral supplementation with high-dose calcitriol and calcium carbonate, she persisted with hypocalcemia and had increased serum phosphorus (5.5 mg/dL) and intact parathyroid hormone (616 pg/mL). Renal replacement therapy was indicated to control the bone mineral disorder but was unsuccessful after 4 months of treatment. Control of the hypocalcemia (Ca 8.6 mg/dL) was only achieved 1 month after lenalidomide withdraw due to thrombocytopenia. Renal replacement therapy was discontinued, and the patient remained on conservative treatment for CKD, with no recurrence of hypocalcemia in the following months. The chronology of events in this case strongly suggests causality between lenalidomide and refractory hypocalcemia. This case report is a warning to hematologists and nephrologists about the potential risk of lenalidomide-induced hypocalcemia in CKD patients.