Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics.
This week: Thiamine
Thiamine (also called vitamin B1) is an essential human nutrient. Thiamine is widespread in various foods, but under some circumstances, deficiency may occur.
- People who consume excessive alcohol are particularly predisposed to deficiency due to factors including inadequate dietary intake, impaired gastrointestinal absorption, and impaired hepatic storage. Deficiency can actually occur due to any condition of unbalanced nutrition that lasts for 2-3 weeks, e.g. malignancy, hyperemesis gravidarum, and use of total parenteral nutrition without adequate thiamine.
- Thiamine deficiency is associated with neurological and cardiovascular signs. Early symptoms may be vague and nonspecific, e.g. fatigue, irritability, and abdominal discomfort. Severe deficiency can lead to the development of beriberi: cardiac, or ‘wet’ beriberi, is characterised by cardiac failure and oedema; ‘dry’ beriberi is characterised by peripheral neuropathy, muscle wasting and weakness, and paralysis.
- Wernicke-Korsakoff syndrome may also develop in severe cases of thiamine deficiency, notably in association with chronic alcoholism. Wernicke’s encephalopathy involves ocular abnormalities, gait ataxia and mental status changes, and can precede or occur concomitantly with Korsakoff’s psychosis, a disorder of short-term memory loss that results in confabulation.
- Only small amounts of thiamine are absorbed from the gastrointestinal tract (the maximum amount absorbed after a single oral dose in healthy subjects is approximately 4.5 mg). Parenteral use is therefore usually recommended in severe deficiency to ensure adequate absorption
- After initial replacement, the usual oral maintenance dose is 100 mg daily
Please consider these issues when preparing or interpreting RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to firstname.lastname@example.org.