What is the recommended dose of Vitamin B1 (Thiamine) for treating and preventing deficiency?

Recommended Dosage of Vitamin B1 (Thiamine) for Treating and Preventing Deficiency

For treating thiamine deficiency, the recommended dosage ranges from 10-300 mg/day orally for mild deficiency to 100-500 mg intravenously three times daily for severe deficiency, with duration and route depending on the severity and clinical presentation. 1

Dosage by Severity of Deficiency

Mild Deficiency

• 10 mg/day orally for one week, followed by 3-5 mg/day orally for at least 6 weeks 1
• Maintenance after proven deficiency: 50-100 mg/day orally 1

Moderate Risk Situations

• Chronic diuretic therapy: 50 mg/day orally 1
• Continuous renal replacement therapy: 100 mg/day 1
• Post-bariatric surgery patients: 200-300 mg daily oral thiamine for the first 3-4 months, particularly for those with symptoms such as dysphagia or vomiting 2

Severe/Acute Deficiency

• Hospitalized patients or critical illness: 100-300 mg/day intravenously 1
• Emergency/intensive care patients: 100-300 mg/day IV for 3-4 days from admission 1
• Wernicke encephalopathy: 500 mg three times daily, intravenously 1
• FDA label for Wernicke-Korsakoff syndrome: Initial dose of 100 mg IV, followed by IM doses of 50-100 mg daily until the patient consumes a regular diet 3

Specific Clinical Scenarios

• Refeeding syndrome: 300 mg IV before initiating nutrition therapy, then 200-300 mg IV daily for at least 3 more days 1
• Alcoholic liver disease with withdrawal symptoms: 100-300 mg/day for 2-3 months 1
• "Wet" beriberi with myocardial failure: Emergency IV administration (FDA label does not specify exact dose) 3
• Patients receiving dextrose: 100 mg thiamine in each of the first few liters of IV fluid to avoid precipitating heart failure 3
• Acute thiamine deficiency disorders in resource-limited settings: 50 mg daily for 5 days 4

Route of Administration Considerations

• For suspected chronic deficiency without acute disease: Oral route is adequate 1
• For acute disease or suspected inadequate intake: IV route is recommended 1
• For patients with alcohol-related gastritis: IV route is preferred due to poor absorption 1
• Important safety consideration: Always administer thiamine before glucose-containing IV fluids to avoid precipitating acute thiamine deficiency 1, 5

Duration of Treatment

• Mild deficiency: At least 6 weeks 1
• Alcoholic liver disease: 2-3 months following resolution of withdrawal symptoms 1
• Alcohol dependence with high risk of deficiency: Parenteral thiamine 250-500 mg/day for 3-5 days, followed by oral thiamine 250-300 mg/day 6
• Uncomplicated alcohol dependence (low risk): Oral thiamine 250-500 mg/day for 3-5 days, followed by oral thiamine 100-250 mg/day 6

Special Considerations and Monitoring

• No upper limit for toxicity has been established; excess thiamine is excreted in urine 1, 2
• High IV doses rarely cause anaphylaxis; doses >400 mg may induce nausea, anorexia, and mild ataxia 1, 2
• Thiamine status should be determined by measuring RBC or whole blood thiamine diphosphate (ThDP) 1
• Monitoring is recommended in patients with suspected deficiency and cardiomyopathy, prolonged diuretic treatment, prolonged medical nutrition, post-bariatric surgery, refeeding syndrome, or encephalopathy 1
• Thiamine deficiency can manifest as peripheral neuropathy, cardiac abnormalities (including QTc prolongation), and neurological symptoms 7

Prevention of Deficiency

• For prevention in high-risk populations: 5-10 mg daily oral supplementation is generally sufficient 3, 4
• For patients undergoing bariatric surgery: Thiamine supplementation is recommended to prevent deficiency 1
• For patients with marginal thiamine status receiving dextrose: 100 mg thiamine hydrochloride in each of the first few liters of IV fluid 3