The delta anion gap/delta HCO3 ratio in patients with a high anion gap metabolic acidosis
- Michael Emmett, MD
Michael Emmett, MD
- Editor-in-Chief — Nephrology
- Section Editor — Fluid and Electrolytes
- Chief of Internal Medicine
- Baylor University Medical Center
- Biff F Palmer, MD
Biff F Palmer, MD
- Professor of Internal Medicine
- University of Texas Southwestern Medical Center
NORMAL SERUM ANION GAP
Determination of the serum anion gap (AG) is an important step in the differential diagnosis of acid-base disorders and especially metabolic acidosis [1-5]. (See "Approach to the adult with metabolic acidosis", section on 'Physiologic interpretation of the serum anion gap'.)
The serum AG is calculated from the following formula, which represents the difference between the primary measured cation (Na) and the primary measured anions (Cl and HCO3):
Serum AG = Na - (Cl + HCO3)
Some clinicians also include the serum potassium in the formula; when this is done, the normal range increases by approximately 4 mEq/L:
Serum AG = (Na + K) - (Cl + HCO3)
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- NORMAL SERUM ANION GAP
- DELTA AG/DELTA HCO3 RATIO
- The delta AG/delta HCO3 in lactic acidosis
- The delta AG/delta HCO3 in ketoacidosis
- The delta AG/delta HCO3 in other causes of high AG acidosis
- - Methanol, ethylene glycol, and other alcohol and glycol poisoning
- - D-lactic acidosis and toluene inhalation
- D-lactic acidosis
- Toluene intoxication
- - Chronic kidney disease
- The delta AG/delta HCO3 in patients with mixed metabolic disorders
- POTENTIAL SOURCES OF ERROR
- SUMMARY AND RECOMMENDATIONS