[A man in his 70s found confused on his training ride]

Lactate Gap: A Diagnostic Support in Severe Metabolic Acidosis of Unknown Origin

Ethylene glycol poisoning is a medical emergency. The metabolites glycolate and glyoxylate give metabolic acidosis. Because of similar structure, these metabolites are misinterpreted as lactate by many point-of-care blood gas analyzers. The falsely high lactate values can lead to misdiagnosis, inappropriate laparotomies, and delayed antidotal therapy. As laboratory analyzers measure plasma lactate only, the difference or the “lactate gap” aids in early diagnosis. We present a patient with severe metabolic acidosis and elevated lactate levels on the point-of-care analyzer. A lactate gap supported the diagnosis of ethylene glycol poisoning. Hemodialysis and fomepizole treatment could be started immediately.