A 61-year-old man presented with an increased anion-gap metabolic acidosis, an increased serum osmolal gap, and a negative result in an alcohol screen. Gas chromatography revealed an increased ethylene glycol (EG)2 concentration (22 mg/dL) and a propylene glycol (PG) result that was below the lower limit of quantification (<5 mg/dL) (Fig. 1A). The patient was treated with hemodialysis, followed by phenytoin and a high-dose lorazepam infusion for a witnessed seizure. By 13 h, the EG concentration had fallen below the lower limit of quantification (<5 mg/dL); however, a peak identified as PG was observed, corresponding to a concentration of 27 mg/dL (Fig. 1B). 

Fig. 1. Chromatograms of EG, PG, and 1,3-propanediol (internal standard). (A), EG peak (22 mg/dL). (B), PG peak (27 mg/dL). +P, enablement of peak detection; −P, disablement of peak detection; 1,3-PRO, 1,3-propanediol.


  1. What are the common causes of EG or PG poisoning?
  2. What could cause a positive EG result and then a positive PG result in this patient?
  3. What is the difference in toxicity between EG and PG?
Read the article here for the answers.