Vitamin B1
Vitaminas e mineraisÚltima revisão: 7 de abril de 2026. Abordagem de fontes: contexto padrão de interpretação laboratorial, material médico de referência e orientações clínicas ou de saúde pública quando relevantes.
O que é Vitamin B1?
Vitamin B1, also known as thiamine, is a water-soluble vitamin that serves as an essential coenzyme in carbohydrate metabolism, energy production, and neural function. Thiamine pyrophosphate (TPP), the biologically active form, is required by key enzymes in the citric acid cycle and the pentose phosphate pathway—metabolic processes that generate ATP (cellular energy) and provide building blocks for DNA and RNA synthesis. The body stores only small amounts of thiamine (approximately 25–30 mg total), with the highest concentrations found in skeletal muscle, heart, liver, kidneys, and brain.
Because thiamine cannot be synthesized by the body and has a relatively short half-life of 9–18 days, regular dietary intake is essential. Rich dietary sources include whole grains, pork, legumes, nuts, and fortified cereals. Thiamine levels in blood are typically measured as whole blood thiamine or erythrocyte transketolase activity, which reflects functional thiamine status. Thiamine deficiency, while relatively uncommon in developed nations due to food fortification, remains a significant clinical concern in chronic alcohol use disorder, bariatric surgery patients, and populations relying heavily on polished rice.
Por que isso importa
Thiamine is indispensable for converting food into usable energy. Deficiency causes two classic syndromes: beriberi (affecting the cardiovascular and peripheral nervous systems) and Wernicke-Korsakoff syndrome (a potentially fatal neurological emergency most commonly seen in chronic alcoholism). Wet beriberi causes heart failure with edema, while dry beriberi causes peripheral neuropathy and muscle wasting. Wernicke encephalopathy—characterized by confusion, ataxia, and eye movement abnormalities—is a medical emergency that requires immediate intravenous thiamine. Early detection and treatment of thiamine deficiency can prevent permanent brain damage.
Faixas de referência normais
| Grupo | Faixa | Unidade |
|---|---|---|
| Adults (whole blood thiamine diphosphate) | 70–180 | nmol/L |
As faixas de referência podem variar entre laboratórios. Sempre compare seus resultados com as faixas fornecidas pelo seu local de exame.
O que significam níveis altos de Thiamine
Causas comuns
- High-dose thiamine supplementation
- Excessive fortified food intake
- Rare—water-soluble vitamin readily excreted by kidneys
Possíveis sintomas
- Generally no adverse effects—excess is excreted in urine
- Very rare reports of allergic reactions with parenteral administration
O que fazer: High thiamine levels are generally not a clinical concern, as excess thiamine is efficiently excreted by the kidneys. No known toxicity has been established for oral thiamine, even at very high doses. Reduce supplementation if levels are significantly above normal, but no specific treatment is typically needed.
O que significam níveis baixos de Thiamine
Causas comuns
- Chronic alcohol use (impairs absorption and increases excretion)
- Malnutrition or restricted diets
- Bariatric surgery or GI surgery
- Prolonged vomiting (hyperemesis gravidarum)
- Chronic diarrhea or malabsorption
- High-dose diuretic use (increases urinary losses)
- Refeeding syndrome in malnourished patients
- Diets high in polished (white) rice
Possíveis sintomas
- Fatigue, irritability, and poor concentration
- Peripheral neuropathy (tingling, numbness in extremities)
- Muscle weakness and wasting
- Rapid heart rate and edema (wet beriberi)
- Confusion, ataxia, and eye abnormalities (Wernicke encephalopathy)
- Memory loss and confabulation (Korsakoff syndrome)
- Anorexia and weight loss
O que fazer: Mild deficiency is treated with oral thiamine supplementation, typically 50–100 mg daily. Suspected Wernicke encephalopathy is a medical emergency requiring immediate high-dose intravenous thiamine (200–500 mg three times daily) before glucose administration—giving glucose without thiamine can precipitate or worsen the condition. Address underlying causes such as alcohol cessation, improved nutrition, and treatment of malabsorption. Hospitalized patients at risk should receive prophylactic thiamine.
Quando o exame de Thiamine é recomendado?
- In patients with chronic alcohol use disorder
- Before and after bariatric surgery
- When neurological symptoms of unknown cause are present
- In cases of unexplained heart failure or peripheral neuropathy
- In malnourished or critically ill patients
- When prolonged vomiting or malabsorption is present
Perguntas frequentes
Biomarcadores relacionados
Referências e abordagem de revisão
As páginas do glossário de biomarcadores são explicações educativas e devem ser interpretadas junto com as faixas de referência e observações fornecidas pelo seu laboratório e pelo seu médico. Para conhecer nossos padrões editoriais e processo de revisão, veja nossa Política editorial e a nossa revisão de conteúdo.
Quer analisar seus níveis de Thiamine?
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Enviar resultados de exames →Aviso médico: Estas informações são apenas educativas e não substituem orientação, diagnóstico ou tratamento médico profissional. As faixas de referência podem variar entre laboratórios. Sempre converse com seu profissional de saúde sobre a interpretação dos seus resultados específicos.