The Myth of the Low Anion Gap
- Robert J. Goldstein, MD;
- Norman S. Lichtenstein, MD;
- Daniel Souder, MD
Abstract
Sixty-seven thousand seven hundred forty consecutive sets of electrolyte levels measured at the Massachusetts General Hospital were reviewed, and their anion gaps were calculated. A low anion gap (less than 8 mEq/L) was found in 304 patients (0.8%). Repeatedly low anion gaps were found in only 19 patients. Eight patients were hypoalbuminemic, and eight were hyponatremic. For the entire population, there was a positive correlation between sodium concentration and anion gap. The average anion gap was 16.25 mEq/L. The most common cause of a low anion gap was presumptive laboratory error.
(JAMA 243:1737-1738, 1980)
Footnotes
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