Renal and acid–base: charge barrier in nephrotic syndrome: 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 · Renal and acid–base: charge barrier in nephrotic syndrome

Sample item

A 5-year-old boy has heavy proteinuria, mostly albumin, and generalised oedema. Light microscopy of the glomeruli is normal. Which physiological defect underlies the proteinuria?

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

The answer and the reasoning

C. Loss of negative charge on the filtration barrier, allowing albumin to pass

In minimal change disease, effacement of podocyte foot processes is accompanied by loss of the anionic charge of the glomerular barrier. Albumin is anionic and normally repelled, so it is lost, whereas larger proteins are still held back (selective proteinuria). The fall in oncotic pressure drives the oedema.

Option by option

  • A. Increased tubular secretion of albumin

    Albumin is not secreted by tubules; it is filtered.

  • B. Large breaks in the glomerular basement membrane

    Large basement membrane breaks would permit loss of larger proteins and cells.

  • C. Loss of negative charge on the filtration barrier, allowing albumin to pass (correct)

    Correct. Loss of the anionic charge barrier allows the negatively charged albumin to be filtered.

  • D. Reduced filtration surface area

    Reduced surface area lowers GFR and does not cause heavy albuminuria.

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 C, Loss of negative charge on the filtration barrier, allowing albumin to pass. In minimal change disease, effacement of podocyte foot processes is accompanied by loss of the anionic charge of the glomerular barrier.

Why is "Increased tubular secretion of albumin" not the answer?

Albumin is not secreted by tubules; it is filtered.

Why is "Large breaks in the glomerular basement membrane" not the answer?

Large basement membrane breaks would permit loss of larger proteins and cells.

Why is "Reduced filtration surface area" not the answer?

Reduced surface area lowers GFR and does not cause heavy albuminuria.

What concept does this question test?

It tests Renal and acid–base: charge barrier in nephrotic syndrome in Physiology. Albumin is anionic and normally repelled, so it is lost, whereas larger proteins are still held back (selective proteinuria). The fall in oncotic pressure drives the oedema.

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 Renal and acid–base: charge barrier in nephrotic syndrome?

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.