Thiamine Deficiency

Key Features

• Most common cause: chronic alcohol use disorder

• Other causes

  • Malabsorption (eg, following bariatric surgery)

  • Dialysis

  • Chronic protein-calorie undernutrition

• Thiamine depletion can be precipitated when patients with low thiamine are given a large carbohydrate load, such as an intravenous dextrose infusion

Clinical Findings

• Early manifestations

  • Anorexia

  • Muscle cramps

  • Paresthesia

  • Irritability

• Advanced deficiency chiefly affects cardiovascular system (wet beriberi) or nervous system (dry beriberi)

• Wet beriberi

  • Occurs with severe physical exertion and high carbohydrate intake

  • Characterized by marked peripheral vasodilation resulting in high-output heart failure with dyspnea, tachycardia, cardiomegaly, pulmonary edema, and peripheral edema with warm extremities

• Dry beriberi

  • Occurs with inactivity and low-calorie intake

  • Involves both peripheral and central nervous systems

  • Peripheral nerve involvement includes symmetric motor and sensory neuropathy with pain, paresthesia, and loss of reflexes in legs more than the arms

  • Central nervous system involvement includes Wernicke encephalopathy (clinical triad of nystagmus progressing to ophthalmoplegia, truncal ataxia, and confusion) and Korsakoff syndrome (amnesia, confabulation, and impaired learning)

Diagnosis

• Clinical response to empiric thiamine therapy

• Biochemical tests

  • Measure thiamine directly

  • Erythrocyte transketolase activity and urinary thiamine excretion

  • Transketolase activity coefficient > 15–20% suggest thiamine deficiency

Treatment

• Thiamine: 50–100 mg intravenously per day for the first few days, followed by 5–10 mg once daily orally

• Therapeutic doses of other water-soluble vitamins

• Treatment results in complete resolution of symptoms and signs in 50% of patients (one-fourth immediately and one-fourth over days); the remaining 50% have only partial resolution or no benefit