What result of thiamin deficiency can be fatal?

• A. Lactic acidosis
• B. Wernicke encephalopathy
• C. Peripheral neuropathy
• D. Anemia

Answer: (A)

Thiamin is a key cofactor for pyruvate dehydrogenase, the enzyme that converts pyruvate from glycolysis into acetyl-CoA for the TCA cycle. When thiamin is deficient, this step falters, causing pyruvate to be reduced to lactate. The resulting lactic acidosis can impair cellular respiration and lead to shock or organ failure, making it a potentially fatal consequence of deficiency. Other manifestations like Wernicke encephalopathy, peripheral neuropathy, or anemia reflect specific organ effects but are not as immediately life-threatening as a severe lactic acidosis.