RESUMO
We describe an overweight but otherwise previously healthy 17-year-old female who presented with altered mental status and rapidly progressive weakness. She was ultimately diagnosed with Wernicke encephalopathy and wet beriberi resulting from severe thiamine deficiency. She required admission to the pediatric ICU because of hypoventilation with progressive weakness and worsening encephalopathy and was found to have impaired cardiac function as assessed by echocardiography. Her heart function and encephalopathy improved on initiation of thiamine repletion. She remained in inpatient rehabilitation for 10 months but still remained weak at discharge. Thiamine deficiency is not commonly considered in the United States as a diagnosis other than in patients with severe alcohol use disorder. However, thiamine may be depleted in as little as 2 weeks if nutrition is inadequate. In such a setting, thiamine deficiency is an important etiology to consider early in the pediatric patient with altered mentation especially because it can be readily and safely treated.