[Vitamin B1 deficiency as cause of a severe lactic acidosis and ileus symptoms]

A 2-year-old boy presented with severe lactic acidosis and ileus symptoms after 3 weeks of parenteral nutrition. Diagnosis of thiamine deficiency was made only when further complications had occurred. This case shows the importance of sufficient substitution of thiamine during parenteral nutrition. In lactic acidosis of unknown etiology thiamine deficiency must be considered.