Urine Anion Gap in NAGMA

NA + K - Cl = surrogate for Urine NH4+

NH4+ is excreted with Cl- as counter-ion, hence increasing negative AG implies ↑ ammonium.

NEGATIVE when the distal acidification is intact:

 - All GI distrubances

 - Proximal RTA

POSITIVE when urinary NH4+ excretion imparied:

 - Distal RTA

 - Type 4 RTA (nb ↑K)

 - Renal Failure



Dr. John Booth @ThePeanutKidney



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