What are the indications for thiamine (Vitamin B1)?

Indications for Thiamine (Vitamin B1)

Thiamine is indicated for the treatment of established thiamine deficiency conditions including Wernicke's encephalopathy, beriberi (both dry and wet forms), and in patients at high risk for deficiency who cannot take oral thiamine due to severe anorexia, nausea, vomiting, or malabsorption. 1

Primary Indications

Thiamine hydrochloride injection is specifically indicated for:

• Treatment of established thiamine deficiency conditions:

  • Wernicke's encephalopathy
  • Infantile beriberi with acute collapse
  • Cardiovascular disease due to thiamine deficiency (wet beriberi)
  • Neurological manifestations (dry beriberi)
  • Neuritis of pregnancy with severe vomiting 1

• Prevention of thiamine deficiency:

  • When administering IV dextrose to individuals with marginal thiamine status (to avoid precipitating heart failure)
  • In patients who cannot take thiamine orally due to severe anorexia, nausea, vomiting, or malabsorption 1

High-Risk Populations Requiring Thiamine Supplementation

Thiamine supplementation is recommended for patients with:

• Prolonged vomiting or poor nutritional intake
• High alcohol intake
• Rapid weight loss
• Malabsorptive conditions (e.g., short bowel syndrome)
• Post-bariatric surgery status 2
• Renal failure requiring dialysis
• Hyperemesis gravidarum 3
• Critically ill patients receiving IV dextrose without thiamine repletion 3
• Unexplained heart failure or lactic acidosis 3

Dosing Recommendations

Dosing varies by clinical condition and severity:

1. Established Wernicke's encephalopathy:

   • 500 mg IV three times daily for 3-5 days 2

2. High suspicion or proven deficiency:

   • 200-300 mg IV three times daily for 3-5 days 2, 4

3. Patients at risk of deficiency:

   • 100 mg IV three times daily 2
   • For post-bariatric surgery patients: 15 mg oral thiamine daily (prophylactic), increased to 200-300 mg daily if symptomatic 2

4. Maintenance dose for proven deficiency:

   • 50-100 mg/day orally 2
   • After parenteral treatment: 250-300 mg/day orally 4

5. Alcohol dependence:

   • High risk: 250-500 mg/day parenteral for 3-5 days, followed by oral thiamine 250-300 mg/day
   • Low risk (uncomplicated alcohol dependence): oral thiamine 250-500 mg/day for 3-5 days, followed by 100-250 mg/day 4

Clinical Manifestations of Thiamine Deficiency

Early recognition is critical as thiamine deficiency can manifest as:

• Lactic acidosis
• Peripheral neuropathy
• Ataxia
• Ocular changes (e.g., nystagmus)
• Advanced symptoms: confabulation, memory loss, psychosis 3
• Cardiovascular manifestations: high-output heart failure (wet beriberi) 5
• Neurological manifestations: neuropathy (dry beriberi) 5

Important Clinical Considerations

• Thiamine status should be determined by measuring RBC or whole blood thiamine diphosphate (ThDP) 2
• Thiamine deficiency is underdiagnosed, particularly in alcoholics and critically ill patients 4, 6
• Treatment should be initiated promptly when deficiency is suspected, as it is safe, inexpensive, and potentially life-saving 6
• Thiamine should be administered before glucose in at-risk patients to prevent precipitating or worsening Wernicke's encephalopathy 1
• While high-quality evidence from randomized controlled trials is limited, clinical experience and case reports support current practice guidelines 7

Common Pitfalls to Avoid

• Failing to administer thiamine before glucose in at-risk patients
• Underdiagnosing thiamine deficiency, especially in alcoholics
• Using inadequate doses for treatment of Wernicke's encephalopathy
• Switching to oral therapy too early in severe deficiency states
• Neglecting to provide prophylactic thiamine to high-risk patients (post-bariatric surgery, alcoholics, malnourished)