Blood: reticulocyte correction: practice question

A Physiology 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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Physiology · Blood: reticulocyte correction

Sample item

A patient has a haematocrit of 20% and a reticulocyte count of 6%. Taking the normal haematocrit as 45%, what is the corrected reticulocyte percentage (before any maturation-time adjustment)?

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

The answer and the reasoning

A. 2.7%

Corrected reticulocyte count = observed reticulocyte percentage multiplied by patient haematocrit divided by normal haematocrit. Here 6 x 20/45 = 2.67, which rounds to 2.7%. The correction is needed because few red cells in the denominator inflate the raw percentage.

Option by option

  • A. 2.7% (correct)

    Correct. 6 x 20/45 = 2.67%.

  • B. 6.0%

    The raw percentage is uncorrected and overstates the marrow output in an anaemic patient.

  • C. 1.5%

    The arithmetic does not produce this value; 20/45 is about 0.44, not 0.25.

  • D. 13.5%

    This results from inverting the fraction (6 x 45/20), which wrongly inflates the count.

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 Physiology question

What is the answer to this Physiology question?

The best answer is A, 2.7%. Corrected reticulocyte count = observed reticulocyte percentage multiplied by patient haematocrit divided by normal haematocrit.

Why is "6.0%" not the answer?

The raw percentage is uncorrected and overstates the marrow output in an anaemic patient.

Why is "1.5%" not the answer?

The arithmetic does not produce this value; 20/45 is about 0.44, not 0.25.

Why is "13.5%" not the answer?

This results from inverting the fraction (6 x 45/20), which wrongly inflates the count.

What concept does this question test?

It tests Blood: reticulocyte correction in Physiology. Here 6 x 20/45 = 2.67, which rounds to 2.7%. The correction is needed because few red cells in the denominator inflate the raw percentage.

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 Blood: reticulocyte correction?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.