Kidney Week

Abstract: SA-PO497

Variability in the Delta Anion Gap/Delta Bicarbonate (ΔAG/ΔHCO3) Ratio in Lactic Acidosis

Session Information

• Acid-Base, Calcium, Potassium, and Magnesium Disorders: Clinical
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

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

Authors

• Yu, Garrett, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, United States

Garrett Yu, MD

• Liu, In-Lu Amy, Kaiser Permanente Department of Research and Evaluation, Pasadena, California, United States

In-Lu Amy Liu

• Treger, Richard M., Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, United States

Richard M. Treger, MD

Background

The delta anion gap (AG) to delta bicarbonate (HCO₃) ratio (ΔAG/ΔHCO₃) is useful for detecting complex acid-base disorders in the setting of elevated anion gap metabolic acidosis. Consistent with published studies, our data demonstrated that ΔAG/ΔHCO₃ in lactic acidosis has significant variability, ranging from 0.07-5.79. This variability is not well explained. This study aims to better understand what factors explain the variability in ΔAG/ΔHCO₃.

Methods

This is a retrospective cohort study of adult ICU patients with sepsis and lactic acidosis. ΔAG/ΔHCO₃ was calculated using albumin-corrected AG and each patient’s baseline AG and HCO_3. Pearson correlation was used to determine the association between creatinine, BUN, BUN/Cr, chloride, and potassium and ΔAG/ΔHCO₃.

Results

484 patients were included. Creatinine (Figure; R² = 0.225; p < 0.0001), BUN (R² = 0.0233; p < 0.026), and serum chloride (R² = 0.045; p = 0.002) were significantly correlated with ΔAG/ΔHCO₃. No association was found between ΔAG/ΔHCO₃ and serum potassium or BUN/Cr

Conclusion

Creatinine and BUN were significantly correlated with ΔAG/ΔHCO₃, likely due to accumulation of organic and inorganic anions that occurs with renal dysfunction. Serum chloride was significantly associated with ΔAG/ΔHCO_3, but only explained 4.5% of variance in ΔAG/ΔHCO₃, suggesting that concurrent normal AG metabolic acidosis (NAGMA), as with large volume saline infusion, diarrhea, or early renal failure did not play a clinically significant role in the variability in ΔAG/ΔHCO_3. Lack of statistically significant association between ΔAG/ΔHCO₃ and serum potassium, as well as BUN/Cr, supports the absence of diarrhea (as a cause of NAGMA) or concurrent metabolic alkalosis, respectively. Additional work needs to be done to identify other important factors that can further explain the variability in ΔAG/ΔHCO₃, which limits the utility of ΔAG/ΔHCO₃ in diagnosing mixed acid-base disorders.