What are the symptoms of thiamine (Vitamin B1) deficiency?

Symptoms of Thiamine Deficiency

Thiamine deficiency presents with a range of neurological, cardiovascular, and gastrointestinal symptoms, with Wernicke-Korsakoff syndrome being the most severe neurological manifestation requiring immediate high-dose intravenous thiamine supplementation. 1, 2

Neurological Manifestations

Thiamine deficiency affects the nervous system in various ways:

• Early neurological symptoms:

  • Mental changes: apathy, decreased short-term memory, confusion, irritability 1
  • Fatigue 3
  • Cognitive deficits 1

• Advanced neurological manifestations:

  • Wernicke's encephalopathy (classic triad: confusion, ocular abnormalities, ataxia) 1, 3
  • Korsakoff's syndrome (severe memory impairment) 4
  • Peripheral neuropathy (dry beriberi) 5, 4
  • Optic neuropathy 1
  • Bilateral lateral rectus palsy 3
  • Lower extremity weakness 5
  • Ataxia (difficulty with coordination) 1, 3

Cardiovascular Manifestations (Wet Beriberi)

Cardiovascular involvement includes:

• Congestive heart failure 6, 4
• Tachycardia
• Peripheral edema
• High-output cardiac failure 4

Gastrointestinal Manifestations

Gastrointestinal symptoms may include:

• Nausea and vomiting (can be early signs of deficiency) 3
• Anorexia
• Gastrointestinal dysfunction 6
• Abdominal pain

Metabolic Manifestations

• Unexplained metabolic lactic acidosis 1, 6
• Anion gap metabolic acidosis 5
• Elevated blood pyruvic acid levels 7, 8

High-Risk Populations

Thiamine deficiency is particularly common in:

• Chronic alcohol users (most common cause in affluent countries) 4, 9
• Patients with malnutrition or poor oral intake 1, 2
• Post-bariatric surgery patients 1, 2
• Patients with prolonged vomiting or malabsorption 2, 5
• Patients at risk for refeeding syndrome 1, 2
• Critically ill patients 2, 6
• Patients with liver cirrhosis 2
• Patients on liquid-only diets 3
• Patients on continuous renal replacement therapy 1, 2

Time Course of Deficiency Development

Body depletion of thiamine can occur after approximately three weeks of total absence of thiamine in the diet 7, 8. However, early signs may appear sooner, especially in high-risk individuals.

Important Clinical Considerations

• Early symptoms like fatigue, nausea, and vomiting are often missed as signs of thiamine deficiency 3
• The classic triad of Wernicke's encephalopathy (confusion, ocular abnormalities, ataxia) may not be present in all cases 3
• Thiamine deficiency should be suspected in any patient with unexplained lactic acidosis, especially in high-risk groups 6
• Prompt treatment with thiamine is essential to prevent permanent neurological damage 3
• Administration of glucose-containing fluids without thiamine supplementation can precipitate or worsen thiamine deficiency in at-risk patients 2

Diagnostic Considerations

Thiamine status can be determined by measuring:

• Red blood cell or whole blood thiamine diphosphate (ThDP) levels 1, 2
• Increased blood pyruvic acid levels (indicate deficiency) 7, 8
• Lactate levels (may be elevated) 1

A therapeutic trial of thiamine supplementation is often diagnostic when clinical suspicion is high, as treatment should not be delayed while awaiting laboratory results 1.