Medical calculators
Anion Gap
Serum Anion Gap
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Anatium is a study resource, not medical advice. Nothing here is a diagnosis, a prescription or a substitute for a clinician who has seen the patient. Check every number against a current local protocol before it touches anyone, and never act on a result you cannot reproduce yourself.
How it is calculated
AG = Na - Cl - HCO₃, without potassium in this version; adding potassium raises the normal range by about 4. Normal about 3-11 mEq/L on modern ion-selective analysers (older texts give 8-12); use the range of your own laboratory. Correct for albumin: the expected gap falls by roughly 2.5 mEq/L for every 10 g/L that albumin is below 40, so a hypoalbuminaemic patient can have a "normal" gap that is really raised.
About
The unmeasured anions in a metabolic acidosis, separating the causes that raise it from those that do not.
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