Toluene

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]])

  • xxx

Arterial Blood Gas (ABG) (see Arterial Blood Gas, [[Arterial Blood Gas]])

  • Metabolic Acidosis

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]])

  • Epidemiology

Other Manifestations

  • Scleroderma-Like Syndrome (see Scleroderma, [[Scleroderma]])
    • Has been reported with toluene exposure

Treatment

  • xxx

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