Vitamin B1 (thiamine) deficiency is the underlying cause of several clinical syndromes, including Wernicke's encephalopathy, wet beriberi, and dry beriberi, rather than a single clinical condition or diagnosis.
Clinical presentation depends on the chronicity of the deficiency.
As signs and symptoms are non-specific, the presence of risk factors raises suspicion of the diagnosis.
Risk factors include alcohol dependence, malabsorption, and a diet low in thiamine (e.g., based on polished rice).
As there is no rapid diagnostic test for the condition, presumptive treatment should be commenced immediately if vitamin B1 deficiency is suspected.
Untreated vitamin B1 deficiency in the form of Wernicke's encephalopathy can result in the need for institutional care, or in death.
Vitamin B1, also known as thiamine, is an essential micronutrient. Deficiency can result in distinct clinical presentations. Acute deficiency can present as Wernicke's encephalopathy with ocular abnormalities, mental state changes, and ataxia. Acute or chronic deficiency can also lead to wet beriberi (which presents as high-output cardiac failure with oedema and orthopnoea), or low-output cardiac failure with lactic acidosis and peripheral cyanosis (also known as Shoshin beriberi). Dry beriberi occurs with chronic deficiency and is characterised by a distal peripheral polyneuropathy.
History and exam
Key diagnostic factors
- presence of risk factors
- ocular abnormalities (Wernicke's encephalopathy)
Other diagnostic factors
- confusion (Wernicke's encephalopathy)
- ataxia (Wernicke's encephalopathy)
- muscle aches
- incessant crying (infantile beri-beri)
- anorexia (infantile beri-beri)
- bulging fontanelle (infantile beri-beri)
- dyspnoea (wet beriberi)
- orthopnoea (wet beriberi)
- tachycardia (wet beriberi)
- peripheral cyanosis (wet beriberi)
- peripheral oedema (wet beriberi)
- decreased sensation (dry beriberi)
- reduced tendon reflexes (dry beriberi)
- muscle weakness (dry beriberi)
- muscle wasting (dry beriberi)
- chronic alcohol excess
- staple diet of polished rice
- age <1 year in endemic thiamine deficient region
- refeeding/total parenteral nutrition
- hyperemesis gravidarum
- recurrent vomiting/chronic diarrhoea
- gastrointestinal surgery
- magnesium deficiency
- HIV infection/AIDS
- cancer and chemotherapy
- thiaminase- and thiamine antagonist-containing diet
- genetic mutation
1st investigations to order
- erythrocyte thiamine pyrophosphate
- thyroid function tests
Investigations to consider
- MRI brain
at-risk asymptomatic hospitalised adults
adults on community alcohol withdrawal
symptomatic children and infants
- Peripheral neuropathy
- Acute encephalitis
- Graves' disease
- ESPEN guideline on clinical nutrition in the intensive care unit
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