Vitamins: riboflavin deficiency: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Vitamins: riboflavin deficiency

Sample item

A 30-year-old woman on a poor diet has angular stomatitis, cheilosis, a magenta tongue and seborrhoeic dermatitis of the nasolabial folds. Which test best confirms the suspected deficiency?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Erythrocyte glutathione reductase activity coefficient

The picture suggests riboflavin deficiency (ariboflavinosis). Glutathione reductase requires FAD, so in deficiency its activity rises markedly when FAD is added in vitro, giving a high activity coefficient. This is the standard functional assay.

Option by option

  • A. Erythrocyte glutathione reductase activity coefficient (correct)

    A raised activity coefficient shows the FAD-dependent enzyme is unsaturated, confirming riboflavin deficiency.

  • B. Serum methylmalonic acid level

    Methylmalonic acid is a marker of vitamin B12 deficiency.

  • C. Urinary N-methylnicotinamide excretion

    Urinary N-methylnicotinamide is used to assess niacin status.

  • D. Erythrocyte transketolase activity with thiamine pyrophosphate

    The transketolase TPP effect assesses thiamine status.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, Erythrocyte glutathione reductase activity coefficient. The picture suggests riboflavin deficiency (ariboflavinosis).

Why is "Serum methylmalonic acid level" not the answer?

Methylmalonic acid is a marker of vitamin B12 deficiency.

Why is "Urinary N-methylnicotinamide excretion" not the answer?

Urinary N-methylnicotinamide is used to assess niacin status.

Why is "Erythrocyte transketolase activity with thiamine pyrophosphate" not the answer?

The transketolase TPP effect assesses thiamine status.

What concept does this question test?

It tests Vitamins: riboflavin deficiency in Biochemistry. Glutathione reductase requires FAD, so in deficiency its activity rises markedly when FAD is added in vitro, giving a high activity coefficient. This is the standard functional assay.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Vitamins: riboflavin deficiency?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.