Hemodialysis: Calcium Variability Linked to Hospitalization and Death

Recent upward trends and greater variability in serum calcium were associated with higher 90-day risks of hospitalization and death among patients receiving maintenance hemodialysis. The findings came from an observational landmark analysis published in Clinical Kidney Journal.

Investigators used data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases IV through VII, covering 2009 through 2022. The analysis included 81,475 patients who contributed 431,618 quarterly landmarks. At each landmark, calcium measurements from the preceding 180 days were summarized by the latest value, mean, slope, residual standard deviation as a measure of instability, and months below 8.6mg/dL or above 10.0mg/dL. All-cause hospitalization and death were assessed during the subsequent 90 days.

During follow-up windows, 68,632 hospitalizations and 12,886 deaths occurred. After full adjustment, the latest calcium value was not associated with hospitalization (hazard ratio [HR], 1.00; 95% CI, 0.98-1.02). In the primary dynamics model, lower mean calcium was associated with hospitalization, while a more positive slope and greater variability were associated with increased hospitalization hazards (HRs, 0.97, 1.10, and 1.15, respectively).

Mortality findings differed. Higher latest and mean calcium were associated with death (HRs, 1.158 and 1.156, respectively). A more positive slope (HR, 1.384) and greater variability (HR, 1.373) were also associated with death. Compared with no months above 10.0mg/dL, time above that threshold for 1 to 2 months was associated with an HR of 1.213 for mortality, increasing to 1.374 for 3 to 6 months.

Adding calcium-dynamics measures to the latest value produced only small gains in discrimination. The authors noted that the observational design precluded causal inference, ionized calcium was unavailable, and the 90-day horizon could not characterize longer-term outcomes. They concluded that longitudinal calcium patterns may provide information beyond a single measurement. Whether reducing calcium instability or sustained high calcium improves outcomes requires further study.

Source: Iseri K, Yamazaki T, Taki I, Hida N. Serum calcium dynamics and risk of all-cause hospitalization and mortality in hemodialysis patients: a landmark analysis from the international DOPPS. Clin Kidney J. 2026; sfag324. doi:10.1093/ckj/sfag324