[Relationship between Hypercalcemia and Renal Function with Eldecalcitol]

Eldecalcitol (ELD), an active vitamin D₃ analog, is extensively prescribed in Japan for the treatment of osteoporosis. However, hypercalcemia remains a significant concern, particularly in patients with impaired renal function. Data on the extent to which renal dysfunction increases the risk of hypercalcemia are limited. This retrospective study investigated the relationship between hypercalcemia and renal function in 212 ELD-treated outpatients at Matsuyama Shimin Hospital. Hypercalcemia was observed in 17.0% of the patients. A weak negative correlation was observed between follow-up serum calcium levels and estimated glomerular filtration rate (eGFR). Receiver operating characteristics (ROC) analysis identified a baseline eGFR cutoff of ≤45.9 mL/min, and propensity score matching (1 : 1) adjusted for 12 covariates, including baseline calcium, demonstrated a significantly higher incidence of hypercalcemia in patients with eGFR ≤45.9 mL/min. These findings indicate that a low baseline eGFR predisposes patients to hypercalcemia during ELD therapy. In clinical practice, patients with baseline eGFR ≤45.9 mL/min may require more frequent calcium monitoring and consideration of alternative treatments such as alfacalcidol, with close collaboration between physicians and pharmacists.