What does thiamine deficiency cause?

Thiamine Deficiency Manifestations

Thiamine deficiency causes a range of neurological, cardiovascular, and metabolic disorders including Wernicke-Korsakoff syndrome, beriberi (wet and dry forms), and metabolic lactic acidosis, with symptoms developing as quickly as 20 days after inadequate intake. 1

Clinical Presentations

Neurological Manifestations

• Neurological symptoms range from mental changes such as apathy, decreased short-term memory, confusion, and irritability to more severe manifestations 1
• Advanced deficiency can lead to Wernicke-Korsakoff encephalopathy, optic neuropathy, Leigh's disease, African Seasonal Ataxia, and central pontine myelinolysis 1
• Dry beriberi affects the nervous system, causing peripheral neuropathy 2
• Myeloneuropathy may develop, requiring prompt treatment to prevent permanent damage 1

Cardiovascular Manifestations

• Wet beriberi affects the cardiovascular system, leading to congestive heart failure 1, 3
• Heart failure due to thiamine deficiency often presents with non-specific symptoms, leading to delayed diagnosis 3
• Thiamine deficiency is found in 6% of ambulatory heart failure patients 1

Metabolic Manifestations

• Unexplained metabolic lactic acidosis is a common presentation of thiamine deficiency 1, 4
• This occurs because thiamine is essential for carbohydrate metabolism, specifically the decarboxylation of pyruvic acid and α-ketoacids 5
• Increased levels of pyruvic acid in the blood indicate vitamin B1 deficiency 5

Gastrointestinal Manifestations

• Gastrointestinal beriberi is a subtype affecting the digestive system that can lead to multisystem involvement 2
• Symptoms include intractable nausea and vomiting, which can further exacerbate the deficiency 2

High-Risk Populations

• Malnutrition, poor oral intake, and chronic alcohol consumption are major risk factors 1, 6
• Patients with malignancies and increased metabolic requirements (e.g., pregnancy) are at risk 1
• Reduced gastrointestinal absorption due to disease or surgery (resections) increases risk 1
• Patients on chronic diuretic therapy or continuous renal replacement therapy may experience increased losses 1
• Obesity pre-bariatric surgery and post-surgery frequently present with deficiency 1
• Critical illness (sepsis, major trauma) puts patients at high risk, with >90% showing deficiency or depletion 1, 4
• Refeeding syndrome is associated with increased mortality and requires immediate thiamine supplementation 1

Biochemical Mechanisms

• Thiamine combines with adenosine triphosphate (ATP) to form thiamine pyrophosphate (ThDP), a coenzyme essential for energy metabolism 5, 7
• ThDP serves as a cofactor for several enzymes involved primarily in carbohydrate catabolism 7
• These enzymes are important in the biosynthesis of neurotransmitters, production of reducing equivalents for oxidant stress defense, and synthesis of pentoses used as nucleic acid precursors 7
• Body stores of thiamine are relatively small and can be depleted after approximately three weeks of total absence from the diet 5, 4

Diagnosis and Treatment

• Thiamine status is best determined by measuring ThDP in whole blood or RBCs, as plasma measurement is not useful 1, 8
• Treatment should not be delayed waiting for laboratory results; a thiamine supplementation trial should be performed to assess clinical benefit 1, 8
• For mild deficiency: 10 mg/day thiamine for a week, followed by 3-5 mg/day for at least 6 weeks 1, 8
• For high suspicion or proven deficiency: 200 mg, 3 times a day, IV 1, 8
• For encephalopathy of uncertain etiology: 500 mg, 3 times a day, IV 1
• For refeeding syndrome: 300 mg IV before initiating nutrition therapy, then 200-300 mg IV daily 1
• Maintenance dose after proven deficiency: 50-100 mg/day, orally 1, 8

Prevention

• Thiamine supplementation of stable food products like flour is an effective, simple, and safe public health measure 6
• Early recognition and supplementation in high-risk groups can prevent serious complications 1, 6
• Oral or intravenous glucose must not be given to people at risk of or with suspected thiamine deficiency as it can precipitate Wernicke-Korsakoff syndrome 1