Heme metabolism: porphyria: 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 · Heme metabolism: porphyria

Sample item

A patient has episodic abdominal pain, neuropathy, psychiatric symptoms, and darkening urine without photosensitivity. Which porphyria is most likely?

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

The answer and the reasoning

A. Acute intermittent porphyria

Acute intermittent porphyria affects heme synthesis and causes neurovisceral symptoms without photosensitivity. Attacks can be precipitated by drugs, fasting, hormonal changes, and alcohol.

Option by option

  • A. Acute intermittent porphyria (correct)

    Correct. Neurovisceral attacks with dark urine and no photosensitivity fit AIP.

  • B. Erythropoietic protoporphyria only

    Erythropoietic protoporphyria has prominent photosensitivity.

  • C. Lead deficiency anemia

    Lead toxicity can affect heme synthesis but does not produce this classic porphyria syndrome.

  • D. Porphyria cutanea tarda

    Porphyria cutanea tarda causes photosensitivity and skin fragility.

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, Acute intermittent porphyria. Acute intermittent porphyria affects heme synthesis and causes neurovisceral symptoms without photosensitivity.

Why is "Erythropoietic protoporphyria only" not the answer?

Erythropoietic protoporphyria has prominent photosensitivity.

Why is "Lead deficiency anemia" not the answer?

Lead toxicity can affect heme synthesis but does not produce this classic porphyria syndrome.

Why is "Porphyria cutanea tarda" not the answer?

Porphyria cutanea tarda causes photosensitivity and skin fragility.

What concept does this question test?

It tests Heme metabolism: porphyria in Biochemistry. Attacks can be precipitated by drugs, fasting, hormonal changes, and alcohol.

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 Heme metabolism: porphyria?

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.