Evaluation of Adjusted Calcium Levels in Patients of Chronic Renal Failure with Hypo-Albuminemia

Abstract

Objective: To compare adjusted calcium levels with ionised Calcium in chronic renal failure patients with hypoalbuminemia for the correct assessment of their Calcium status.

Study Design: Cross-sectional study.

Place and Duration of Study: Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Mar 2020 to Jan 2021.

Methodology: A total of 304 individuals aged 18 to 90 years, of either gender were included in the study. Participants were differentiated into stages of Chronic renal failure based on the estimated glomerular filtration rate calculated through the Chronic Kidney Disease Epidemiology Collaboration equation. Serum total Calcium, urea and creatinine were analysed on ADVIA 1800R Clinical Chemistry Auto analyser. In addition, ionised Calcium was analysed on Cobas b221 blood gas and electrolyte analyser.

Results: Mean age of the study participants was 56.3±16.03 years. 130(42.5%) individuals had stage-5 while 102(33.3%) had stage 4 chronic kidney disease. Based on ionised Calcium concentration, 37.3% of participants had hypocalcaemia, 57.2% had normocalcaemia, and 4.9% had hypercalcaemia. 57.5% had albumin concentration between 20-29g/L. Cohen’s Kappa statistical analysis showed adjusted Calcium to be a poor predictor of the correct Calcium status of the patients with hypoalbuminemia.

Conclusion: Adjusted Calcium, using the Modified Payne formula, overestimates Calcium status in patients of chronic renal failure with hypoalbuminemia when compared with total unadjusted Calcium levels hence misclassifying true hypocalcaemic patients as normocalcaemic.
Keywords: Adjusted calcium, Chronic renal failure, Estimated glomerular filtration rate, Hypoalbuminemia, Ionised calcium.