An 18-year-old male has been brought to the emergency department for altered mental status. His friends report that he was at a party when he became incoherent and developed slurred speech, so they called 911. No other history is available.
On examination, he is drowsy and has slurred speech. His temperature is 36.7 C (98 F), blood pressure is 90/60 mm Hg, pulse is 96/min and respirations are 22/min. No focal neurologic findings are present and the general physical examination is unremarkable.
The patient's labs reveal:

Which of the following is the most likely cause of this patient's illness?

Question

An 18-year-old male has been brought to the emergency department for altered mental status.  His friends report that he was at a party when he became incoherent and developed slurred speech, so they called 911.  No other history is available.
On examination, he is drowsy and has slurred speech.  His temperature is 36.7 C (98 F), blood pressure is 90/60 mm Hg, pulse is 96/min and respirations are 22/min.  No focal neurologic findings are present and the general physical examination is unremarkable.
The patient's labs reveal:

Which of the following is the most likely cause of this patient's illness?

Quizplus · Accepted Answer

This patient has metabolic acidosis with a high anion gap of 28 (normally 10-14) and a high osmolar gap of 23, as calculated by the formula (see exhibit). An osmolar gap >10 indicates an unmeasured small molecular weight substance in the blood such as ethanol (most common), methanol, ethylene glycol, or isopropyl alcohol. The table below summarizes the clinical features of various toxicities causing a high osmolar gap. see exhibit 11ec193a_96a6_4849_853d_d934ca633717_MD0002_00 Ethanol's contribution to the osmolar gap in this patient is the blood alcohol (10 mg/dL) divided by 4.5, or about 2. Methanol is a small molecular weight alcohol found in photocopying fluid and de-icing solutions, such as windshield wiper fluids. Methanol is metabolized by alcohol dehydrogenase to formaldehyde and formic acid, and is associated with both increased anion gap metabolic acidosis and elevated osmolar gap. Untreated methanol intoxication can result in permanent retinal damage, blindness, and neurologic dysfunction. Fomepizole (preferred) or ethanol treats methanol toxicity by competing with alcohol dehydrogenase. (Choice A) Isopropyl alcohol ingestion can result in a high osmolar gap and prominent ketosis, but it does not result in an increased anion gap or metabolic acidosis. (Choice B) Several forms of ketoacidosis (diabetic, starvation and alcohol-induced) can result in an increased anion gap metabolic acidosis. The lack of ketones on urinalysis does not support this diagnosis. (Choice C) Lactic acidosis is one of the most common causes of increased anion gap metabolic acidosis, and usually associated with a clinical disorder causing hemodynamic instability. Lactic acidosis does not produce this magnitude of osmolar gap. (Choice E) Salicylate ingestion can cause increased anion gap metabolic acidosis, often in combination with respiratory alkalosis. Salicylate intoxication also does not produce a significant osmolar gap. Educational objective: Both methanol and ethylene glycol toxicities are associated with an increased anion gap metabolic acidosis and an elevated osmolar gap. Methanol is toxic to the retina and ethylene glycol is toxic to the kidney. Isopropyl alcohol toxicity is associated with an elevated osmolar gap, but NOT an increased anion gap metabolic acidosis. __________ References: Toxic alcohol ingestions: clinical features, diagnosis and management (http://www.ncbi.nlm.nih.gov/pubmed/18045860)

An 18-Year-Old Male Has Been Brought to the Emergency Department