Thiamine and riboflavin deficiency vs Niacin and pyridoxine deficiency
How to tell Thiamine and riboflavin deficiency and Niacin and pyridoxine deficiency apart when a board question makes them look alike.
B1 is Wernicke/beriberi; B2 is cheilosis/corneal vascularization; B3 is pellagra; B6 is sideroblastic anemia, neuropathy, and seizures.
Side by side
Thiamine deficiency causes Wernicke-Korsakoff, dry/wet beriberi, and impaired pyruvate/alpha-ketoglutarate dehydrogenase; riboflavin deficiency causes cheilosis, corneal vascularization, and glossitis.
Niacin deficiency causes pellagra with dermatitis, diarrhea, dementia; pyridoxine deficiency causes neuropathy, sideroblastic anemia, seizures, and isoniazid association.
B1 supports oxidative decarboxylation and transketolase; B2 forms FAD/FMN for redox enzymes.
B3 forms NAD/NADP for redox metabolism; B6 forms PLP for transamination, decarboxylation, heme synthesis, and neurotransmitters.
Ophthalmoplegia, ataxia, confusion, high-output heart failure, or low transketolase support B1; cheilosis/glossitis support B2.
Photosensitive dermatitis/diarrhea/dementia supports B3; sideroblastic anemia or seizures after isoniazid supports B6.
The trap
Several B vitamins affect nerves, so anchor on the signature skin, mouth, eye, anemia, and alcohol/isoniazid clues.
The repair move
For B-vitamin questions, attach each vitamin to its cofactor role and one exam-defining syndrome.
Try a free question
CoreA 52-year-old man with chronic alcohol use disorder is admitted for confusion, gait ataxia, and horizontal nystagmus with bilateral lateral rectus weakness. After being given IV glucose without thiamine, his confusion worsens. Which deficiency best explains his presentation?
Show answer and explanation
Answer: A. Thiamine (B1) deficiency. Wernicke encephalopathy is thiamine deficiency, classic triad of confusion, ataxia, and ophthalmoplegia, and is precipitated by glucose loading without thiamine in alcoholics. Always give thiamine BEFORE glucose. Pyruvate and alpha-ketoglutarate dehydrogenases require thiamine pyrophosphate.
Why the other choices are tempting
- B. Riboflavin deficiency causes cheilosis, angular stomatitis, glossitis, and corneal vascularization, not Wernicke encephalopathy.
- C. Niacin deficiency causes pellagra with dermatitis, diarrhea, dementia.
- D. Pyridoxine deficiency causes sideroblastic anemia and peripheral neuropathy, not the Wernicke triad.
- E. B12 deficiency causes megaloblastic anemia and posterior column disease, not the rapid-onset Wernicke triad after glucose loading.
Flashcards
Tap a card to flip it.
What clue supports Thiamine and riboflavin deficiency?
Choose Thiamine and riboflavin deficiency when the stem gives this pattern: Thiamine deficiency causes Wernicke-Korsakoff, dry/wet beriberi, and impaired pyruvate/alpha-ketoglutarate dehydrogenase; riboflavin deficiency causes cheilosis, corneal vascularization, and glossitis.
What clue supports Niacin and pyridoxine deficiency?
Choose Niacin and pyridoxine deficiency when the stem gives this contrasting pattern: Niacin deficiency causes pellagra with dermatitis, diarrhea, dementia; pyridoxine deficiency causes neuropathy, sideroblastic anemia, seizures, and isoniazid association.
Quick answers
What is the fastest way to tell Thiamine and riboflavin deficiency from Niacin and pyridoxine deficiency?
B1 is Wernicke/beriberi; B2 is cheilosis/corneal vascularization; B3 is pellagra; B6 is sideroblastic anemia, neuropathy, and seizures.
What is the key clue for Thiamine and riboflavin deficiency?
Thiamine deficiency causes Wernicke-Korsakoff, dry/wet beriberi, and impaired pyruvate/alpha-ketoglutarate dehydrogenase; riboflavin deficiency causes cheilosis, corneal vascularization, and glossitis.
What is the key clue for Niacin and pyridoxine deficiency?
Niacin deficiency causes pellagra with dermatitis, diarrhea, dementia; pyridoxine deficiency causes neuropathy, sideroblastic anemia, seizures, and isoniazid association.
What is the common trap with Thiamine and riboflavin deficiency vs Niacin and pyridoxine deficiency?
Several B vitamins affect nerves, so anchor on the signature skin, mouth, eye, anemia, and alcohol/isoniazid clues.