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Veterinarians use a rapid, qualitative, colorimetric blood test when they suspect ethylene glycol ingestion in animals. To evaluate the sensitivity and specificity of this 30-minute test in humans, investigators analyzed 24 blood samples from patients with suspected ingestion of ethylene glycol or methanol that were submitted to a reference laboratory. The samples initially were analyzed by standard gas chromatography to determine the presence of ethylene glycol or methanol. Then, a technician performed the qualitative ethylene glycol test, and three physicians blinded to gas chromatography results evaluated the color change as negative or positive.
Ethylene glycol levels ranged from 27 to 281 mg/dL. Interobserver agreement for the qualitative test results was high (κ=0.909). The qualitative test had a sensitivity of 100% and a specificity of 89% for identifying the presence of ethylene glycol. The color change for one sample that tested negative for both alcohols by gas chromatography was interpreted as positive by one physician and as negative by two: This result was considered false-positive.
Long H et al. A rapid qualitative test for suspected ethylene glycol poisoning. Acad Emerg Med 2008 Jul; 15:688.
Comment
The definitive diagnosis of toxic alcohol poisoning by laboratory confirmation often takes too long if samples must be sent to a reference laboratory. Thus, treatment of toxic alcohol ingestion often is initiated based on clinical suspicion plus laboratory findings such as anion gap acidosis or elevated osmolar gap. A rapid, accurate, qualitative test would be useful to prevent unnecessary, expensive, and potentially harmful treatment. Although more study is needed, this rapid qualitative test looks promising.