Approach
The mainstay of treatment is thiamine replacement therapy.[1]
In addition to the treatment of patients with symptoms of vitamin B1 deficiency, thiamine supplementation should be considered in all patients at high risk of deficiency.
Vitamin B1 deficiency is a clinical diagnosis, and as the presenting symptoms are non-specific, thiamine replacement therapy should be initiated immediately based on any suspicion of the deficiency. Treatment should not be delayed while awaiting the results of further investigations to exclude other diagnoses. Toxicity due to thiamine supplementation is unlikely; excess thiamine is excreted in the urine.[1]
There are insufficient data from randomised controlled trials to recommend standard doses for the treatment of vitamin B1 deficiency.[63] Dosing regimens are therefore based on consensus expert opinion. As oral thiamine is poorly absorbed, it should be given intravenously in the hospital setting in acute disease.[1]
Refeeding can be a risk factor for precipitating Wernicke's encephalopathy. Thiamine should be given before initiating oral, enteral, or parenteral feeding (including intravenous glucose therapy) in patients identified as being at risk for refeeding syndrome.[20]
Treatment of symptomatic or at-risk asymptomatic hospitalised adults
High-dose intravenous thiamine should be given for 3 days and the clinical response assessed.
If there is evidence of clinical improvement, intravenous thiamine should be continued at a lower dose for a further 5 days, or until clinical improvement ceases.
If there is no clinical improvement, high-dose intravenous thiamine should be discontinued. Oral thiamine may be continued at lower doses in these patients.
All asymptomatic adults at high risk of vitamin B1 deficiency should be considered for 3 days of high-dose intravenous thiamine.
Although rare, anaphylaxis and anaphylactoid reactions can occur when thiamine is given parenterally.[1][13] It is therefore recommended that intravenous thiamine is administered in hospital (with facilities for cardiopulmonary resuscitation).[7]
Magnesium, potassium, and phosphate levels should be measured, and replacement therapy initiated per standard protocols.[20]
Supplementation during community alcohol withdrawal programmes
Prophylactic oral thiamine should be offered to patients who misuse alcohol before and during medically assisted alcohol withdrawal.[64]
Treatment of symptomatic children and infants
Vitamin B1 deficiency in infants and children is extremely rare in developed countries.
Infants (both breastfed and bottle-fed) with symptomatic vitamin B1 deficiency should be treated with a slow intravenous infusion of thiamine, followed by 7 days of intramuscular thiamine, and 3 to 6 weeks of oral therapy thereafter. Bottle-fed infants should receive formula milk fortified with thiamine in addition to the above thiamine supplementation.
Mothers of breastfed infants with vitamin B1 deficiency should also be treated with 7 weeks of oral thiamine.[65]
There are no established doses for thiamine replacement in children with symptomatic vitamin B1 deficiency, but it may be appropriate to treat young children with the same dosing regimen as that given to infants.
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