Measurement of ionized calcium with a point-of-care ionometer during etelcalcetide therapy

Hypocalcemia is a common and clinically significant side effect of etelcalcetide therapy. The aim of this study was to evaluate the utility of ionized calcium (iCa) measurements with a point-of-care ionometer compared to albumin-corrected total calcium and to assess the incidence of hypocalcemia in patients receiving etelcalcetide therapy using pre-dialysis iCa values.

This was a phase IV, non-interventional, prospective, single-arm, observational study. A total of 20 chronic hemodialysis patients were included in the study. The iCa concentration was determined before dialysis using a point-of-care ionometer (GEM Premier 3000) at the patient's bedside. Hypocalcemia was defined by a pre-dialysis iCa concentration of less than 0.90 mmol/L.

Pre-dialysis corrected total calcium and iCa decreased over time during treatment with etelcalcetide. A statistically significant linear association was observed between point-of-care iCa and albumin-corrected calcium (r = 0.532, p = 0.019; R² = 0.283). Visual comparisons generally showed parallel behavior, but only a moderate correlation. Of 240 iCa values measured, 3 cases (1.25%) were < 0.90 mmol/L and 20 cases (8.3%) were between 0.90 and 0.96 mmol/L.

Our results highlight the value of direct iCa monitoring as a practical and sensitive tool for detecting hypocalcemia and guiding etelcalcetide therapy. Bedside measurement enabled timely dialysate calcium adjustments, preventing clinically significant hypocalcemia and treatment discontinuation. Point-of-care iCa monitoring offers a safer, more responsive strategy for optimizing calcium management in hemodialysis patients.