Inflammation: exudate and transudate: practice question

A Pathology 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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Pathology · Inflammation: exudate and transudate

Sample item

A 55-year-old man with fever and cough has a pleural effusion. Pleural fluid protein is 4.2 g/dL (serum 6.0 g/dL) and pleural fluid LDH is 350 U/L (serum 450 U/L, upper reference limit 220 U/L). What is the correct interpretation?

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

The answer and the reasoning

C. Exudate from increased vascular permeability, as in parapneumonic effusion

Light's criteria classify an effusion as an exudate if any one is met: fluid-to-serum protein ratio above 0.5, fluid-to-serum LDH ratio above 0.6, or fluid LDH above two-thirds of the upper reference limit. Here the protein ratio is 4.2 / 6.0 = 0.7 and the LDH ratio is 350 / 450 = 0.78, both exceeding the cut-offs. Exudates reflect inflammation with increased permeability, whereas transudates have a low protein content.

Option by option

  • A. Transudate from raised hydrostatic pressure, as in heart failure

    Heart failure produces a transudate with protein ratio below 0.5, which does not fit the values.

  • B. Transudate from sodium and water retention, as in cirrhosis

    Cirrhotic effusions are transudates with low protein, which does not fit these figures.

  • C. Exudate from increased vascular permeability, as in parapneumonic effusion (correct)

    Correct. Both ratios exceed the cut-offs, which points to inflammatory leakage as in pneumonia.

  • D. Transudate from reduced oncotic pressure, as in nephrotic syndrome

    Hypoalbuminaemia in nephrotic syndrome produces a low-protein transudate, which does not fit.

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 Pathology question

What is the answer to this Pathology question?

The best answer is C, Exudate from increased vascular permeability, as in parapneumonic effusion. Light's criteria classify an effusion as an exudate if any one is met: fluid-to-serum protein ratio above 0.

Why is "Transudate from raised hydrostatic pressure, as in heart failure" not the answer?

Heart failure produces a transudate with protein ratio below 0.5, which does not fit the values.

Why is "Transudate from sodium and water retention, as in cirrhosis" not the answer?

Cirrhotic effusions are transudates with low protein, which does not fit these figures.

Why is "Transudate from reduced oncotic pressure, as in nephrotic syndrome" not the answer?

Hypoalbuminaemia in nephrotic syndrome produces a low-protein transudate, which does not fit.

What concept does this question test?

It tests Inflammation: exudate and transudate in Pathology. 5, fluid-to-serum LDH ratio above 0.6, or fluid LDH above two-thirds of the upper reference limit. Here the protein ratio is 4.2 / 6.0 = 0.7 and the LDH ratio is 350 / 450 = 0.78, both exceeding the cut-offs. Exudates reflect inflammation with increased permeability, whereas transudates have a low protein content.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Inflammation: exudate and transudate?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.