What are the causes of thiamine deficiency?

Causes of Thiamine Deficiency

Thiamine deficiency develops through several mechanisms, including insufficient dietary intake, malabsorption, increased metabolic demands, and increased glucose administration, with body stores being limited (25-30 mg) and dependent on regular dietary intake. 1

Primary Mechanisms of Thiamine Deficiency

Thiamine deficiency occurs through multiple pathways:

1. Insufficient dietary intake:

   • Body stores of thiamine are limited (25-30 mg)
   • Depletion can occur after approximately three weeks of total absence in diet 2
   • Regular dietary intake is essential due to thiamine's short half-life 1

2. Increased metabolic demands:

   • Higher carbohydrate intake increases thiamine requirements 2
   • Critical illness increases metabolic needs 1
   • Pregnancy and lactation increase requirements 1

3. Malabsorption:

   • Gastrointestinal disorders affecting absorption 1, 3
   • Post-bariatric surgery 1
   • Prolonged vomiting or diarrhea 1

4. Biochemical interference:

   • Administration of glucose-containing fluids without thiamine supplementation can precipitate acute deficiency 1
   • Thiamine combines with ATP to form thiamine pyrophosphate (cocarboxylase), essential for carbohydrate metabolism 2

High-Risk Populations

Several groups are at elevated risk for thiamine deficiency:

Alcohol Use Disorder

• Most common and well-recognized risk factor 1, 4, 3
• Multiple mechanisms involved:
  • Poor dietary intake
  • Impaired intestinal absorption
  • Decreased hepatic storage
  • Impaired thiamine utilization

Medical Conditions

• Patients with liver cirrhosis, particularly alcoholic liver disease 1
• ICU patients with critical illness 1, 3
• Cancer patients, especially those with appetite loss 5
• End-stage renal disease 3
• Heart failure 3
• Severe burns 3
• Post-major surgery 3
• Septic shock 3

Nutritional Risk Factors

• Refeeding syndrome 1, 3
• Prolonged parenteral nutrition without adequate supplementation 1
• Strict vegetarian diets 1
• Calorie-restricted diets 1
• Malnutrition from any cause 1, 3

Other Vulnerable Groups

• Elderly individuals (≥65 years) 1
• Institutionalized patients 1
• Dark-skinned or veiled individuals with limited sun exposure 1
• Pregnant or lactating women 1

Clinical Implications

Thiamine plays crucial roles in:

• Carbohydrate metabolism as a coenzyme for pyruvate dehydrogenase 1, 2
• Energy production and mitochondrial function 1, 6
• Proper functioning of central and peripheral nervous systems 6
• Neurotransmitter synthesis 6

Deficiency can lead to:

• Wernicke-Korsakoff syndrome, a potentially fatal neurological disorder 4, 6
• Dry beriberi (neurological manifestations) 3
• Wet beriberi (cardiovascular manifestations) 3
• Mitochondrial dysfunction and oxidative stress 7
• Lactic acidosis 7, 6
• Blood-brain barrier disruption 7

Important Clinical Pearls

• Thiamine should be administered before any glucose-containing fluids to prevent precipitating acute thiamine deficiency 1
• Diagnosis can be challenging as many patients don't exhibit all typical symptoms 5
• Prolonged appetite loss (>2 weeks) may be an early indicator of thiamine deficiency 5
• Patients receiving chemotherapy may be at greater risk for developing thiamine deficiency 5
• Increased levels of pyruvic acid in the blood indicate vitamin B1 deficiency 2
• Treatment with thiamine supplementation is safe, inexpensive, simple, and potentially life-saving 3