• Also called thiamine.
• Function
  • In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions:
    • α-ketoglutarate dehydrogenase (TCA cycle)
    • Transketolase (HMP shunt)
    • Branched-chain ketoacid dehydrogenase (catabolism of branched chain amino acids leucine, isoleucine & valine)
    • Pyruvate dehydrogenase (links glycolysis to TCA cycle)
    • Think ATBP
• Deficiency:
  • Impaired glucose breakdown → ATP depletion worsened by glucose infusion (increased metabolites of glucose); highly aerobic tissues (eg, brain, heart) are affected first.
  • In alcoholic or malnourished patients, give thiamine before dextrose to ↓ risk of precipitating Wernicke encephalopathy.
  • Diagnosis made by ↑ in RBC transketolase activity following vitamin B1 administration.
  • Spell beriberi as Ber1Ber1 to remember vitamin B1.
  • Wernicke-Korsakoff syndrome
    • Wernicke syndrome (classic triad)):
      • Confusion: Disorientation, apathy, decreased attention span. Responds well to treatment.
      • Ophthalmoplegia: Damage to CN III, IV, and vestibular nuclei. Rapidly reversible.
      • Ataxia: Damage to cerebellar cortex, vestibular nuclei. Takes longer to resolve, may be permanent.
    • Korsakoff syndrome: Damage to anterior and medial dorsal nucleus of thalamus, mammillary bodies.
      • Confabulation (when unsure of a fact, will fill in with a fabricated story that they themselves believe to be true)
      • Personality change
      • Memory loss, anterograde amnesia (permanent).
  • Dry beriberi—polyneuropathy, symmetrical muscle wasting.
  • Wet beriberi—high-output cardiac failure (dilated cardiomyopathy), edema.