Elevated Lactate Secondary to Gastrointestinal Beriberi.

Thiamine deficiency usually occurs with prolonged nutritional deficiency and is almost universally identified with Wernicke's encephalopathy or beriberi. It is also, however, a rare cause of elevated lactate and gastroenterological symptoms. This case report describes a 30-year-old man with 2 weeks of gastroenterological symptoms and intermittent oral intake, who was found to have an elevated lactate level. Neurological exam was normal and an extensive workup was negative, but after being treated with thiamine, his lactate level improved overnight and all of his symptoms resolved. Thiamine levels returned low at 44 nmol/L (normal 78-185 nmol/L). Lack of recognition of this phenomenon, while rare, can lead to unnecessary tests and procedures and increased morbidity and mortality.