Mass methanol poisoning: a clinico-biochemical analysis of 10 cases

Methanol is a common ingredient in many household products and intoxication can arise easily from inadvertent exposure through ingestion, inhalation or percutaneous absorption. We analysed ten cases of methanol poisoning who presented with visual, neurological and gastrointestinal symptoms, of whom one died and nine were successfully detoxified with ethanol and bicarbonate infusions. Clinical symptoms were not found to correlate with the severity of poisoning. Serum methanol level was found to correlate significantly with arterial pH (correlation coefficient -0.74, p = 0.014) and serum standard bicarbonate levels (correlation coefficient -0.87, p = 0.001). We found that an arterial pH of < 7.33 or a serum standard bicarbonate of < 20 mmol/L correlated well with a serum methanol level of > 45 mg/dL ie severe poisoning (X2 test with Yate's correction factor, p < 0.02). We conclude that arterial pH or serum standard bicarbonate levels can be used as surrogate indicators of the severity of methanol poisoning. They can be used to guide physicians in the method of detoxification (ie whether intravenous or oral ethanol or dialysis should be used) whilst awaiting serum methanol levels in cases where the index of suspicion for methanol poisoning is high. Some cases of severe poisoning can be successfully treated with oral ethanol if the intravenous form is not available.