Nephrology and electrolytes: Fanconi syndrome: practice question

A General Medicine 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.

Try it

General Medicine · Nephrology and electrolytes: Fanconi syndrome

Sample item

A 30-year-old man starts a tenofovir-containing antiretroviral regimen. Months later he has bone pain, serum phosphate is low, urine shows glucose despite a normal blood glucose, and there is generalised aminoaciduria with a normal anion gap metabolic acidosis. Which part of the nephron is damaged?

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

The answer and the reasoning

D. Proximal tubule

Fanconi syndrome is generalised proximal tubular dysfunction, with wasting of phosphate, glucose, amino acids, uric acid and bicarbonate. Tenofovir is a well-known cause, and phosphate loss leads to osteomalacia. Stopping the drug usually helps.

Option by option

  • A. Distal convoluted tubule

    A distal tubule defect causes hypomagnesaemia and hypocalciuria without glycosuria or aminoaciduria.

  • B. Thick ascending limb

    The thick ascending limb defect gives a loop-diuretic-like picture with hypercalciuria.

  • C. Intercalated cells of the collecting duct

    Intercalated cell dysfunction causes distal renal tubular acidosis, without glycosuria or aminoaciduria.

  • D. Proximal tubule (correct)

    Correct. Combined wasting of glucose, phosphate, amino acids and bicarbonate points to the proximal tubule.

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.

More General Medicine questions

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is D, Proximal tubule. Fanconi syndrome is generalised proximal tubular dysfunction, with wasting of phosphate, glucose, amino acids, uric acid and bicarbonate.

Why is "Distal convoluted tubule" not the answer?

A distal tubule defect causes hypomagnesaemia and hypocalciuria without glycosuria or aminoaciduria.

Why is "Thick ascending limb" not the answer?

The thick ascending limb defect gives a loop-diuretic-like picture with hypercalciuria.

Why is "Intercalated cells of the collecting duct" not the answer?

Intercalated cell dysfunction causes distal renal tubular acidosis, without glycosuria or aminoaciduria.

What concept does this question test?

It tests Nephrology and electrolytes: Fanconi syndrome in General Medicine. Tenofovir is a well-known cause, and phosphate loss leads to osteomalacia. Stopping the drug usually helps.

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 Nephrology and electrolytes: Fanconi syndrome?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.