Thiamine Deficiency

Most common cause: alcoholism

Other causes

• Malabsorption

• Dialysis

• Chronic protein-calorie undernutrition

In patients with marginal thiamine stores, symptoms and signs can be precipitated by intravenous dextrose solutions

Early manifestations

• Anorexia

• Muscle cramps

• Paresthesias

• 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, peripheral edema, and 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, paresthesias, and loss of reflexes in legs more than the arms

• Central nervous system involvement includes Wernicke encephalopathy (clinical triad of ophthalmoplegia, nystagmus, ataxia and confusion) and Korsakoff syndrome (amnestic disorder)

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

Thiamine, 50–100 mg intravenously initially, 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% obtain only partial resolution or no benefit