Androgen modulators: finasteride: practice question

A Pharmacology 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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Pharmacology · Androgen modulators: finasteride

Sample item

A 64-year-old man with benign prostatic hyperplasia has been on finasteride for a year and his PSA is 2.4 ng/mL. How should this value be interpreted?

AIt is falsely high, because finasteride raises PSA by about halfBIt is entirely reliable, because finasteride has no effect on PSACIt corresponds to a true PSA of about 5 ng/mL, because finasteride lowers PSA by roughly halfDIt cannot be interpreted until the drug is stopped for one year

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

The answer and the reasoning

C. It corresponds to a true PSA of about 5 ng/mL, because finasteride lowers PSA by roughly half

Finasteride inhibits type 2 5-alpha-reductase, blocking conversion of testosterone to dihydrotestosterone, which shrinks the prostate over months. It also lowers serum PSA by about 50% after 6 to 12 months, so the measured value is doubled for interpretation. Sexual dysfunction and reduced libido are the main adverse effects.

Option by option

A. It is falsely high, because finasteride raises PSA by about half
The drug reduces PSA and does not raise it.
B. It is entirely reliable, because finasteride has no effect on PSA
Finasteride does lower PSA, so a measured value understates the true level.
C. It corresponds to a true PSA of about 5 ng/mL, because finasteride lowers PSA by roughly half (correct)
Correct. Doubling the measured value gives an estimate of the true PSA on treatment.
D. It cannot be interpreted until the drug is stopped for one year
Interpretation is possible by doubling the value, and stopping the drug for a year is unnecessary.

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.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is C, It corresponds to a true PSA of about 5 ng/mL, because finasteride lowers PSA by roughly half. Finasteride inhibits type 2 5-alpha-reductase, blocking conversion of testosterone to dihydrotestosterone, which shrinks the prostate over months.

Why is "It is falsely high, because finasteride raises PSA by about half" not the answer?

The drug reduces PSA and does not raise it.

Why is "It is entirely reliable, because finasteride has no effect on PSA" not the answer?

Finasteride does lower PSA, so a measured value understates the true level.

Why is "It cannot be interpreted until the drug is stopped for one year" not the answer?

Interpretation is possible by doubling the value, and stopping the drug for a year is unnecessary.

What concept does this question test?

It tests Androgen modulators: finasteride in Pharmacology. It also lowers serum PSA by about 50% after 6 to 12 months, so the measured value is doubled for interpretation. Sexual dysfunction and reduced libido are the main adverse effects.

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 Androgen modulators: finasteride?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology 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.