Thiamine Deficiency

 Thiamin (vitamin B1) is a water soluble vitamin

· It is an important cofactor for enzymes involved in amino-acid and carbohydrate metabolism

· Found in many food products including yeast, legumes, pork, rice, and cereals.

· Unlike most water-soluble vitamins, fruits and vegetables are poor sources of thiamine

· Thiamine is denatured at high pH and high temperatures; so, cooking, baking, and canning of some foods (as well as pasteurization) can destroy thiamine

· Thiamine is absorbed in the small intestine (mostly in the jejunum and ileum)

· After absorption, thiamine is bound to albumin and carried by the portal circulation to the liver

· Thiamine deficiency can occur in any patient with nutritional deficiency (alcoholism is often the most common predisposing factor, but is not the only cause).  Other causes include: hyperemesis gravidarum, hemodialysis, malignancy, use of TPN without adequate thiamine, and gastric bypass surgery

· Thiamine deficiency has been associated with 3 main disorders:

o   Beriberi: dry or wet. Dry beriberi is a symmetrical peripheral neuropathy characterized by sensory and motor deficits, mostly in the LE. Wet beriberi includes a neuropathy, as well as signs of cardiomyopathy/heart failure.

o   Wernicke-Korsakoff syndrome: refers to 2 different syndromes:  

§  Wernicke's encephalopathy is an acute syndrome, characterized by the triad of ocular findings (nystagmus or ophthalmoplegia) ataxia, and confusion—requires emergent treatment to prevent death and neurologic morbidity

§  Korsakoff's syndrome refers to a chronic neurologic condition that usually occurs as a consequence of wernicke’s: characterized by impaired short-term memory and confabulation (but normal cognition)

o   Leigh's syndrome: a very rare condition (<100 cases reported) of subacute necrotizing encephalomyopathy characterized by ataxia, dysarthria, areflexia and movement disorders (caused by necrosis and demyelinating changes in the CNS and peripheral nerves)

 

· Progresssion of Wernicke’s encephalopathy can lead to severe neurologic and cardiac dysfunction and can be fatal, if not treated early.

· Treatment involves immediate initiation of parenteral thiamine (preferably IV), which should be continued for at least several days, then switched to PO.  Some of the changes of Wernicke’s are reversible if treated early, although the symptoms of Korsakoff’s (confabulation etc.) are often permanent.

(Victoria Kelly MD, 12/9/10)