ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on X

Kidney Week

Abstract: SA-OR45

The ΔAG/ΔHCO3 Ratio in Lactic Acidosis: Time for a New Baseline?

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Lu, Deborah Dee, Department of Nephrology and Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, United States
  • Treger, Richard M., Department of Nephrology and Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, United States
  • Song, Hubert, Kaiser Permanente Department of Research and Evaluation, Pasadena, California, United States
Background

The ratio of Δanion gap and Δbicarbonate (ΔAG/ΔHCO3) is used to detect co-existing acid-base disorders in patients with high anion gap (AG) metabolic acidosis. Prior studies demonstrating that in lactic acidosis (LA) the ΔAG/ΔHCO3 is approximately 1.6-1.8:1 used mean normal values for anion gap and serum HCO3. This study is the first to examine the ΔAG/ΔHCO3 using each patient’s individual baseline AG and serum HCO3.

Methods

This was a retrospective cohort study of adult Kaiser Permanente Southern California (KPSC) health system members admitted to the ICU with sepsis. Baseline AG and albumin measurements were obtained 1-24 months prior to ICU admission. An albumin-corrected ΔAG/ΔHCO3 ratio was calculated using each patient’s individual baseline AG and serum HCO3. The association between ΔHCO3 and ΔAG was examined using Pearson correlation, a linear regression model was constructed, and 95% prediction limits were computed.

Results

293 patients were included. ΔAG/ΔHCO3 was calculated for 177 patients who had elevated serum lactate levels (>1.9 mM). The mean ΔAG/ΔHCO3 for all patients with elevated serum lactate levels was 1.44 (SD 1.89). The correlation between ΔHCO3 and ΔAG with 95% prediction limits is shown in Figure 1.

Conclusion

The mean ΔAG/ΔHCO3 was 1.44. To our knowledge, this is the first study to determine the ΔAG/ΔHCO3 using each patient’s individual baseline AG and serum HCO3. This has important clinical implications given the wide interindividual variability in AG and HCO3. Regardless, even using the baseline AG and serum HCO3 to calculate the ΔAG/ΔHCO3, the wide 95% prediction limits (Figure 1) suggest that ΔAG/ΔHCO3 should be used cautiously in the diagnosis of mixed acid-base disorders.

Figure 1: Correlation between ΔHCO3 and ΔAG

Funding

  • Commercial Support – The research is supported by a grant from the Regional Research Committee of Kaiser Permanente. Grant No. KP-RRC-20210504.