Thiamine Deficiency Treatment
For severe thiamine deficiency with neurological symptoms (including Wernicke's encephalopathy), administer 500 mg IV thiamine three times daily, and for moderate deficiency give 100 mg IV three times daily, followed by transition to oral maintenance dosing of 50-100 mg/day. 1, 2, 3
Treatment Algorithm Based on Severity
Severe Deficiency with Neurological Symptoms
- Administer 500 mg IV thiamine three times daily for patients presenting with Wernicke's encephalopathy, severe cardiovascular symptoms, or acute neurological manifestations 1
- IV thiamine is FDA-approved for rapid restoration when thiamine deficiency causes dry beriberi (nervous system symptoms) or wet beriberi (cardiovascular symptoms) 2, 3
- Clinical improvement typically occurs within hours to 1 day of administration in severe cases 4
- After initial IV treatment, transition to oral maintenance of 50-100 mg/day 1
Moderate Risk or Deficiency
- Give 100 mg IV thiamine three times daily for patients with moderate deficiency or significant risk factors 1
- This dosing is appropriate when oral intake is compromised but neurological symptoms are not yet severe 1
Mild Deficiency
- Start with 10 mg/day oral thiamine for one week, followed by 3-5 mg daily for at least 6 weeks 1
- This regimen is suitable for patients with laboratory-confirmed or clinically suspected mild deficiency who can tolerate oral intake 1
Special Clinical Situations
Refeeding Syndrome Prevention
- Administer 300 mg IV thiamine before initiating nutrition therapy, followed by 200-300 mg IV daily for at least 3 more days 1
- This prevents precipitation of heart failure when giving IV dextrose to individuals with marginal thiamine status 2, 3
- Thiamine reserves can be depleted within 20 days of inadequate intake, making prophylaxis critical 1, 4
Critically Ill Patients
- Provide 100-300 mg/day thiamine for patients in intensive care settings 1
- Thiamine deficiency is common in sepsis, major surgery, severe burns, and can contribute to unexplained lactic acidosis, heart failure, and delirium 5
- IV thiamine can correct lactic acidosis and improve cardiac function in these patients 5
Chronic Diuretic Therapy
- Give 50 mg oral thiamine daily to patients on long-term diuretics due to increased urinary losses 1
Continuous Renal Replacement Therapy
- Provide 100 mg thiamine daily due to increased losses during dialysis 1
Alcohol Use Disorder
- For suspected Wernicke's encephalopathy: 250-300 mg parenteral thiamine twice daily for 3-5 days, followed by oral 250-300 mg/day 6
- For established Wernicke's encephalopathy: 200-500 mg parenteral thiamine three times daily for 3-5 days, followed by oral 250-1000 mg/day 6
Lactating Mothers
- Treat with 200-300 mg oral thiamine daily when deficiency is suspected to prevent infantile thiamine deficiency 4
Critical Clinical Pearls
Do Not Delay Treatment
- Start thiamine immediately when deficiency is suspected—do not wait for laboratory confirmation 1, 4
- Untreated thiamine deficiency can cause death within days to weeks 4
- A therapeutic trial is appropriate as treatment should not be delayed 1
Safety Profile
- There is no established upper limit for thiamine toxicity, as excess is excreted in urine 1, 4
- Toxicity is rare even with high doses, though doses exceeding 400 mg daily may cause mild side effects (nausea, anorexia, mild ataxia) 7
- Treatment is safe, inexpensive, simple, and life-saving 8
High-Risk Populations to Screen
- Malnutrition, prolonged vomiting, poor dietary intake, high alcohol intake 1
- Rapid weight loss, bariatric surgery patients 1
- Patients unable to tolerate vitamin supplements or with severe anorexia, nausea, vomiting, or malabsorption 1, 2, 3
- Critically ill patients, those with septic shock, end-stage renal disease, heart failure 5, 8
Laboratory Testing
- Red blood cell or whole blood thiamine diphosphate (ThDP) is more reliable than plasma levels 1
- However, diagnosis is often clinical, and response to treatment confirms the diagnosis 8