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
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 about 4 meq/L:
Serum AG = (Na + K) - (Cl + HCO3)
- Rose BD, Post TW. Clinical Physiology of Acid-Base and Electrolyte Disorders, 5th ed, McGraw-Hill, New York 2001. p.583.
- Emmett M, Narins RG. Clinical use of the anion gap. Medicine (Baltimore) 1977; 56:38.
- Gabow PA. Disorders associated with an altered anion gap. Kidney Int 1985; 27:472.
- Kraut JA, Madias NE. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol 2007; 2:162.
- Rastegar A. Use of the DeltaAG/DeltaHCO3- ratio in the diagnosis of mixed acid-base disorders. J Am Soc Nephrol 2007; 18:2429.
- Winter SD, Pearson JR, Gabow PA, et al. The fall of the serum anion gap. Arch Intern Med 1990; 150:311.
- Salem MM, Mujais SK. Gaps in the anion gap. Arch Intern Med 1992; 152:1625.
- Feldman M, Soni N, Dickson B. Influence of hypoalbuminemia or hyperalbuminemia on the serum anion gap. J Lab Clin Med 2005; 146:317.
- Oh MS, Carroll HJ, Goldstein DA, Fein IA. Hyperchloremic acidosis during the recovery phase of diabetic ketosis. Ann Intern Med 1978; 89:925.
- Fernandez PC, Cohen RM, Feldman GM. The concept of bicarbonate distribution space: the crucial role of body buffers. Kidney Int 1989; 36:747.
- Orringer CE, Eustace JC, Wunsch CD, Gardner LB. Natural history of lactic acidosis after grand-mal seizures. A model for the study of an anion-gap acidosis not associated with hyperkalemia. N Engl J Med 1977; 297:796.
- Madias NE, Homer SM, Johns CA, Cohen JJ. Hypochloremia as a consequence of anion gap metabolic acidosis. J Lab Clin Med 1984; 104:15.
- Adrogué HJ, Eknoyan G, Suki WK. Diabetic ketoacidosis: role of the kidney in the acid-base homeostasis re-evaluated. Kidney Int 1984; 25:591.
- Adrogué HJ, Wilson H, Boyd AE 3rd, et al. Plasma acid-base patterns in diabetic ketoacidosis. N Engl J Med 1982; 307:1603.
- Carlisle EJ, Donnelly SM, Vasuvattakul S, et al. Glue-sniffing and distal renal tubular acidosis: sticking to the facts. J Am Soc Nephrol 1991; 1:1019.
- Wallia R, Greenberg A, Piraino B, et al. Serum electrolyte patterns in end-stage renal disease. Am J Kidney Dis 1986; 8:98.
- Narins RG, Emmett M. Simple and mixed acid-base disorders: a practical approach. Medicine (Baltimore) 1980; 59:161.
- Widmer B, Gerhardt RE, Harrington JT, Cohen JJ. Serum electrolyte and acid base composition. The influence of graded degrees of chronic renal failure. Arch Intern Med 1979; 139:1099.
- Hakim RM, Lazarus JM. Biochemical parameters in chronic renal failure. Am J Kidney Dis 1988; 11:238.
- Wang F, Butler T, Rabbani GH, Jones PK. The acidosis of cholera. Contributions of hyperproteinemia, lactic acidemia, and hyperphosphatemia to an increased serum anion gap. N Engl J Med 1986; 315:1591.
- Kebler R, McDonald FD, Cadnapaphornchai P. Dynamic changes in serum phosphorus levels in diabetic ketoacidosis. Am J Med 1985; 79:571.
- 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 anion gap acidosis
- - 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