II. Definition
- Difference between calculated serum anions and cations
III. Calculation: Anion Gap
- AG = Serum Sodium - Serum Chloride - Serum Bicarbonate
- AG = uAnions - uCations
IV. Calculation: Corrected Anion Gap (severe hypoalbuminemia)
- Corrected Anion Gap indicated when Serum Albumin is very low
- AGcorr = AGact + 2.5 * (AlbNl - AlbAct)
- Where AGcorr is Anion Gap corrected
- Where AGact is the measured, actual Anion Gap
- Where AlbNl is the normal albumin
- Where AlbAct is the measured, actual albumin
V. Interpretation
- Normal Anion Gap: 12 +/- 2 meq/L
VI. Causes: Low Anion Gap
- Paraproteinemia (Multiple Myeloma)
- Spurious Hyperchloremia (Bromide toxicity)
- Hyponatremia
- Hypermagnesemia
- Hypoalbuminemia
- See Corrected Anion Gap above
- Anion Gap decreases 2.5 meq per 1 g/dl Albumin drop
VII. Causes: High Anion Gap
- Metabolic Acidosis with high Anion Gap (without increased Serum Chloride)
- Severe alkalemia (albumin become negatively charged)
VIII. References
- Killu and Sarani (2016) Fundamental Critical Care Support, p. 93-114
- Bakerman (1984) ABCs of Lab Data, ILD, Greenville, NC
- Ghosh (2000) Fed Pract p. 23-33
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Related Studies
Concepts | Clinical Attribute (T201) |
MSH | D000136 |
SnomedCT | 102637000 |
LNC | LP30809-5, MTHU015314 |
English | Anion Gaps, Gap, Anion, Gaps, Anion, Anion gap, function, anion gap, AG - Anion gap, Anion gap, Anion gap, function (observable entity), Anion gap (function), Anion Gap |
Portuguese | Gap Aniônico |
Spanish | Anión Gap, anión gap, anion gap, anión restante, brecha aniónica (entidad observable), brecha aniónica (función), brecha aniónica, hiato aniónico, intervalo aniónico |
French | Trou anionique |
German | Anionen-Lücke |
Italian | Gap anionico |
Czech | AG, anion gap, aniontová mezera |
Norwegian | Anion gap |
Dutch | Anion gap |