Nephrology

Urine Anion Gap

Evaluates the cause of a Normal Anion Gap Metabolic Acidosis (NAGMA).

Parameters

mEq/L
mEq/L
mEq/L

Urine Anion Gap Result

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FormulaUrine Anion Gap = (Urine Na + Urine K) - Urine Cl

Clinical Pearls

A simple non-invasive way to measure urinary ammonium (which isn't routinely tested) to track down the etiology of a NAGMA.

Limitations

Not accurate if there is substantial polyuria or excretion of unmeasured urinary anions like ketones, penicillin, or salicylate.