Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 29-08: Thiamine (B1) Deficiency + Key Features Download Section PDF Listen +++ ++ 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 + Clinical Findings Download Section PDF Listen +++ ++ 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) + Diagnosis Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ 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