Exposures
- Glue Sniffing
- Paint Sniffing
Physiology
- Toluene is Metabolized to Benzoic Acid and Ultimately to Hippurate (An Acid Anion)
- For every molecule of toluene metabolized, one hydrogen ion is added -> titration of the hydrogen ions by extracellular bicarbonate lowers the serum bicarbonate concentration
- Benzoic Acid is Excreted in the Urine as Sodium/Potassium Salts
- Hippurate is Excreted in the Urine as Sodium/Potassium Salts, As Well as Being Actively Secreted by the Proximal Tubule
- Results in potassium depletion
- Result: hypokalemic metabolic acidosis
- If most of the acid anions are excreted in the urine, the patient presents with a non-anion gap acidosis, that mimics distal RTA
- If some of the anions are retained, the patient presents with an anion gap metabolic acidosis
Diagnosis
Serum Potassium
- Hypokalemia (see Hypokalemia, [[Hypokalemia]]): the low serum potassium concentration in toluene intoxication implies extremely severe potassium depletion because acidosis usually shifts potassium out of cells
Serum Anion Gap (see Serum Anion Gap, [[Serum Anion Gap]])
Arterial Blood Gas (ABG) (see Arterial Blood Gas, [[Arterial Blood Gas]])
Clinical Manifestations
Neurologic Manifestations
- Quadriparesis (see xxxx, [[xxxx]]): in cases with severe hypokalemia
Renal Manifestations
Anion Gap Metabolic Acidosis (AGMA) (see Metabolic Acidosis-Elevated Anion Gap, [[Metabolic Acidosis-Elevated Anion Gap]])
- Epidemiology
- Occurs Early in the Course
- Occurs With Impaired Renal Function
- Diagnosis: delta anion gap/delta bicarbonate ratio is typically <1
- Due to the typically efficient renal excretion of hippurate, anion gap may not be very elevated
Non-Anion Gap Metabolic Acidosis (NAGMA) (see Metabolic Acidosis-Normal Anion Gap, [[Metabolic Acidosis-Normal Anion Gap]])
- Epidemiology
- Occurs Late in the Course
- Occurs With Intact Renal Function: due to renal excretion of sodium and potassium hippurate
- Clinical
Elevated Osmolal Gap (see Serum Osmolality, [[Serum Osmolality]])
- Physiology: due to the presence of the osmotically-active solute, toluene
Hypokalemia (see Hypokalemia, [[Hypokalemia]])
Other Manifestations
- Scleroderma-Like Syndrome (see Scleroderma, [[Scleroderma]])
- Has been reported with toluene exposure
Treatment
References
- Syndromes of toluene sniffing in adults. Ann Intern Med 1981; 94:758
- Glue-sniffing and distal renal tubular acidosis: sticking to the facts. J Am Soc Nephrol 1991; 1:1019-1027