Artifactual elevation of lactate in ethylene glycol poisoning.

The diagnosis of ethylene glycol poisoning is based on nonspecific clinical symptoms and signs and indirect and direct laboratory measurement. Few institutions have timely access to direct measurement of ethylene glycol. As a result, diagnosis sometimes can be delayed and therapy initiated late. We present two cases of ethylene glycol poisoning. These cases demonstrate the need to recognize the false elevation of lactate in some chemistry analyzers due to the interference of glycolic acid, a metabolite of ethylene glycol. Using the "lactate gap" in comparing the measurement of lactate with two commonly used chemical analyzers aids in differentiating ethylene glycol poisoning from lactic acidosis.