Adjusted Anion Gap Is Associated with Glomerular Filtration Rate Decline in Chronic Kidney Disease

Abstract

Background: Metabolic acidosis is known to accelerate the progression of chronic kidney disease (CKD). However, whether undetermined anions as indicated by the adjusted anion gap (aAG) are associated with estimated glomerular filtration rate (eGFR) decline in patients with CKD is unclear. Methods: Data from 42 patients with CKD (baseline eGFR, 7.1-52.0 ml/min/ 1.73 m²) without massive proteinuria (urinary protein-creatinine ratio, UPCR Results: The mean baseline eGFR was 27.5 ± 11.1 ml/min/1.73 m² and the mean %ΔeGFR/6m was 13.8 ± 10.3. UPCR and aAG were 1.13 ± 0.93 and 9.48 ± 1.88, respectively. %ΔeGFR/6m was associated with aAG (r = 0.438, p < 0.005), but not with UPCR (r = 0.194, p = 0.218). In multivariate linear regression analyses, aAG remained significantly associated with %ΔeGFR/6m (β = 0.45, p < 0.01) after controlling for age, baseline eGFR, UPCR and HCO₃^- concentration. Conclusion: These data suggest that aAG appears to be associated with the progression of CKD. aAG might be an independent predictor of CKD progression.