Urine Anion Gap

Batlle DC, Hizon M, Cohen E, Gutterman C, Gupta R. The use of the urinary anion gap in the diagnosis of hyperchloremic metabolic acidosis. UAG = Na⁺ + K⁺ − Cl⁻ as a rough index of urinary ammonium: negative in diarrhoea (−20 ± 5.7 mmol/L) and in normal subjects given NH₄Cl (−27 ± 9.8), positive in all patients with altered distal urinary acidification (distal RTA, hyperkalaemic distal RTA, selective aldosterone deficiency).