Toluene inhalation (e.g. due to paint or glue sniffing) causes a metabolic acidosis due to its metabolism to hippuric and benzoic acids.
The anion gap is usually not increased as hippurate and benzoate anions are rapidly excreted.
Urine ammonium is appropriately high for the acidosis ( in contrast to renal tubular acidosis where it is inappropriately low).
Toluene inhalation can be confirmed by measuring hippuric acid in a urine specimen (this is sent to Christchurch and turnaround time is usually a week or more).