USMLE

Vitamin B1 (Thiamine) Deficiency

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Vitamins
  1. Vitamin B1 (Thiamine) Biochemistry
  2. Vitamin B1 (Thiamine) Deficiency
  3. Vitamin B2 (Riboflavin)
  4. Vitamin B3 (Niacin) Biochemistry
  5. Vitamin B3 (Niacin) Deficiency and Excess
  6. Hartnup Disease
  7. Vitamin B5 (Pantothenic Acid)
  8. Vitamin B6 (Pyridoxine)
  9. Vitamin B7 (Biotin)
  10. Vitamin B9 (Folate)
  11. Vitamin B12 (Cobalamin) Biochemistry
  12. Vitamins B9 and B12 Deficiencies
  13. Vitamin A (Retinol) Biochemistry
  14. Vitamin A (Retinol) Deficiency and Excess
  15. Vitamin C (Ascorbic Acid) Biochemistry
  16. Vitamin C (Ascorbic Acid) Deficiency and Excess
  17. Vitamin D Biochemistry
  18. Vitamin D Deficiency and Excess
  19. Vitamin E (Tocopherol/Tocotrienol)
  20. Vitamin K Biochemistry
  21. Vitamin K Deficiency
  22. Zinc
  23. Kwashiorkor and Marasmus

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.