The serum anion gap is altered in early kidney disease and associates with mortality Matthew K. Abramowitz, Thomas H. Hostetter, Michal L. Melamed Kidney International Volume 82, Issue 6, Pages 701-709 (September 2012) DOI: 10.1038/ki.2012.196 Copyright © 2012 International Society of Nephrology Terms and Conditions
Figure 1 Graphical depiction of components of the anion gap (AG) in each version of the calculation. Anion gap=Unmeasured anions (UA) – Unmeasured cations (UC). UA and UC are determined by the anions and cations that are accounted for in the calculation. Each panel depicts the components included in each AG calculation. The following definitions were used: Traditional AG=serum sodium(mEq/l) – (serum chloride(mEq/l)+serum bicarbonate(mEq/l)); Albumin-adjusted AG=Traditional AG – (2.5 × serum albumin(g/dl)); Full AG=Albumin-adjusted AG+serum potassium(mEq/l)+ionized calcium(mEq/l) – serum phosphate(mEq/l). The traditional AG calculation includes only Na+, Cl−, and HCO3−. As additional anions and cations are accounted for in the calculation of the albumin-adjusted and full AG, the unmeasured components (UA and UC) become smaller. Kidney International 2012 82, 701-709DOI: (10.1038/ki.2012.196) Copyright © 2012 International Society of Nephrology Terms and Conditions
Figure 2 Mean age-standardized anion gap by categories of creatinine-based Chronic Kidney Disease Epidemiology Collaboration estimated glomerular filtration rate in 11,957 participants (upper panel) and cystatin C-based estimated glomerular filtration rate in 4,132 participants (lower panel) of NHANES 1999–2004. Kidney International 2012 82, 701-709DOI: (10.1038/ki.2012.196) Copyright © 2012 International Society of Nephrology Terms and Conditions
Figure 3 Unadjusted relative hazard of all-cause mortality per one standard deviation higher full anion gap (s.d.=2.49 mEq/l) within quartiles of serum phosphate (upper panel) and albumin (lower panel) in 11,957 participants of NHANES 1999–2004. Kidney International 2012 82, 701-709DOI: (10.1038/ki.2012.196) Copyright © 2012 International Society of Nephrology Terms and Conditions