Exposures

• Glue Sniffing
• Paint Sniffing

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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

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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

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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
  • Type 1 Distal Renal Tubular Acidosis (RTA) (see Type 1 Distal Renal Tubular Acidosis, [[Type 1 Distal Renal Tubular Acidosis]])

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

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Treatment

• xxx

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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