Hypercalcemia caused by oral fosfomycin in a patient with chronic kidney disease who received a living-donor kidney allograft: A case report

Abstract

Patients with chronic kidney disease who have impaired kidney calcium excretion are susceptible to calcium overload -induced hypercalcemia. However, hypercalcemias resulting from fosfomycin calcium hydrate (FOM-Ca) remain unknown. Therefore, this report presents a case of hypercalcemia suggested by FOM-Ca in a patient with chronic kidney disease a living -donor kidney allograft recipient. The patient, a woman in her 40s, underwent a living donor kidney transplant from her mother when she was 25 years old. Her Scr level was approximately 1.70 mg/dL. The patient was admitted to the hospital due to infectious enteritis and initiated on FOM-Ca 2 g/day. Although she recovered from the enteritis, her serum calcium and Scr levels increased from 10.6 mg/dL and 1.69 mg/dL at admission to 12.1 mg/dL and 1.93 mg/dL on the fifth day of hospitalization, respectively. Given the impaired baseline renal function of the patient, we initially investigated the possibility of exogenous calcium or vitamin D overload as the differential diagnosis of hypercalcemia. Drug-induced hypercalcemia caused by FOM-Ca was speculated; therefore, FOM-Ca administration was discontinued. Serum calcium and Scr levels improved to 10.7 mg/dL and 1.66 mg/dL, respectively, on the 10th day of hospitalization. When administering FOM-Ca to patients with chronic kidney disease and impaired calcium–parathyroid hormone balance, monitoring serum calcium concentration is essential. This is crucial owing to the potential risk of developing hypercalcemia from calcium loading.