Vitamin B1 (Thiamine) Deficiency

Summary

Thiamine (Vitamin B1) Deficiency is common in alcoholics and malnourished patients. The clinical picture of Vitamin B1 deficiency is known as beriberi, of which there are two main types: dry beriberi and wet beriberi. Dry beriberi describes neurological symptoms, and includes Wernicke encephalopathy and Korsakoff syndrome. Classically, Wernicke encephalopathy is characterized by confusion (encephalopathy), ataxia, and nystagmus. Korsakoff syndrome is a more severe finding that includes confabulations. Radiographic imaging of these patients typically reveals lesions at the mamillary bodies and thalamus. Wet beriberi describes cardiovascular effects of thiamine deficiency, and can include high output heart failure and dilated cardiomyopathy.

Key Points

• Vitamin B1 (Thiamine) Deficiency
  • Classically seen in chronic alcoholism
  • Worsened by glucose/dextrose infusion
    • Systemic uptake of glucose increases utilization of already low thiamine levels, leading to thiamine depletion in highly aerobic tissues (brain, heart)
    • In alcoholic or malnourished patients, give thiamine before dextrose to lower risk of precipitating acute Wernicke encephalopathy
  • Syndromes of Deficiency
    • Dry beriberi = neurologic problems (“nerves are dry”)
      • Polyneuropathy, symmetrical muscle wasting
      • Wernicke encephalopathy (acute)
        • Classic triad of confusion, ophthalmoplegia/nystagmus, ataxia
      • Korsakoff psychosis (chronic)
        • Confabulation, personality change, memory loss (permanent)
    • Wet beriberi = cardiac problems (“blood is wet”)
      • High-output heart failure, dilated cardiomyopathy
  • Radiologic Findings
    • Damage to mammillary bodies and medial dorsal nucleus of thalamus

Find Thiamine Deficiency and other Vitamins among Pixorize's visual mnemonics for the USMLE Step 1 and NBME shelf exams.