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Anion Gap

Abbreviation: AG

Panel: Metabolic, Kidney & Electrolytes · All metabolic & kidney tests

Typical adult reference range

Conventional units8–16 mEq/L
SI units8–16 mmol/L

Ranges vary between laboratories and methods — compare your result with the range printed on your own report.

What a high or low result can mean

High anion gap: high values can be seen in lactic acidosis, ketoacidosis, kidney failure, and some poisonings.

Low anion gap: low values are uncommon and can be seen with low albumin or certain paraproteins.

These are associations, not a diagnosis: the same result can have several causes, and your clinician interprets it with the rest of your results and history.

Good to know

Calculated from sodium, chloride, and bicarbonate.

◆ Kidney note

This test is closely tied to kidney health, and it is one a kidney specialist (nephrologist) watches closely. On this site, kidney-related results are a special focus: see the kidney and dialysis medicines in our Drug Guide and the kidney condition hubs for the wider picture.

Related tests — Metabolic, Kidney & Electrolytes

AlbuminAmylaseBeta-HydroxybutyrateBicarbonateBlood Urea NitrogenBUN-to-Creatinine RatioCalcium, TotalChloride
Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.