Do you still use the urinary anion gap to estimate renal ammonium excretion in patients with a non-anion gap metabolic acidosis, given its limitations?

Yes, I do, but especially as a teaching tool to help understand the make-up of urine in different clinical scenarios. Of course, a urine NH4+ would make this all so much easier, but I believe that the UAG is usually still of value in the evaluation of a NAGMA.

The Achilles heel of it, of course, is ...

Yes, I still use the urine anion gap (UAG) in clinical practice. While its limitations are well recognized, most hospitals currently lack the capability to directly measure urinary ammonium. It would be preferable to measure NH4+ if this were available, however, I do not think we should completely t...

I use both urinary anion gap and urinary osmolal gap to estimate renal ammonium excretion in patients with a non-anion metabolic acidosis. In clinical settings, in which ammonium is excreted with a non-chloride anion, the urinary osmolal gap will be more reliable in estimating renal ammonium excreti...

Yes, I still use the urine anion gap - I like to use it for teaching purposes, but also it is sometimes easier to obtain. Even at our institution, urine ammonia is a send out and can take at least 48 hours to come back.

No, I do not use the urinary anion gap to estimate urinary ammonium since it has been demonstrated that the urinary anion gap does not estimate urinary ammonium (DOI: Uribarri & Oh, PMID 33769949, DOI: Uribarri et al., PMID 35810828). However, since urinary anion gap is positive in renal acidosis (a...

Thanks to all the erudite answers from the experts above.

Please also see the recent article by Battle et al., PMID 40279177.