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Updated: Oct 10, 2026

A Semi-Automated and Reproducible Biological-Based Method to Quantify Calcium Deposition In Vitro
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A Semi-Automated and Reproducible Biological-Based Method to Quantify Calcium Deposition In Vitro

Published on: June 2, 2022

Albumin-corrected calcium and ionized calcium in stable haemodialysis patients

C M Clase1, G L Norman, M L Beecroft

  • 1Division of Nephrology, Dalhousie University, Halifax, NS, Canada.

Nephrology, Dialysis, Transplantation : Official Publication of the European Dialysis and Transplant Association - European Renal Association
|November 10, 2000
PubMed

Insights

Total calcium measurement is not a reliable indicator of ionized calcium levels in dialysis patients. Published correction formulas do not improve accuracy; direct ionized calcium measurement is recommended when results are uncertain.

Area of Science:

  • Nephrology
  • Clinical Chemistry

Background:

  • Ionized calcium is the physiologically active form, but total calcium is routinely measured.
  • Existing formulas to correct total calcium for albumin binding lack validation in dialysis patients.

Purpose of the Study:

  • To evaluate the accuracy of corrected calcium formulas compared to measured ionized calcium in dialysis patients.
  • To determine if standard correction formulas improve calcium assessment in this population.

Main Methods:

  • Simultaneous measurement of ionized calcium, total calcium, albumin, total protein, and pH before dialysis.
  • Study included 50 stable outpatients and convalescent inpatients undergoing dialysis.
  • Measurements were standardized using z scores for comparison.

Main Results:

  • Despite calcium supplementation, 22% of patients had ionized hypocalcemia.
  • Published correction formulas showed poor agreement with measured ionized calcium.
  • The Payne formula, commonly used, performed worse than uncorrected total calcium.

Conclusions:

  • Correction formulas for calcium in dialysis patients are not recommended.
  • Uncorrected total calcium measurements are more reliable than corrected values.
  • Direct measurement of ionized calcium is advised for accurate assessment in dialysis patients.
Abstract

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