Electrolytes: salt-wasting tubulopathy: 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.

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General Medicine · Electrolytes: salt-wasting tubulopathy

Sample item

A 22-year-old woman has muscle cramps and tetany. Blood pressure is 100/60 mmHg. Investigations show potassium 2.8 mmol/L, magnesium 0.5 mmol/L, serum bicarbonate 32 mmol/L and a low urinary calcium excretion. She does not take diuretics. Which condition is most likely?

ABartter syndromeBPrimary hyperaldosteronismCLiddle syndromeDGitelman syndrome

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

The answer and the reasoning

D. Gitelman syndrome

Gitelman syndrome is an autosomal recessive loss of function of the thiazide-sensitive Na-Cl cotransporter in the distal tubule. It mimics chronic thiazide use, with hypokalaemia, metabolic alkalosis, hypomagnesaemia and hypocalciuria, and it presents in adolescence or adulthood with normal or low blood pressure.

Option by option

A. Bartter syndrome
Bartter syndrome affects the loop transporter, causes hypercalciuria, and presents in infancy or childhood.
B. Primary hyperaldosteronism
Primary hyperaldosteronism causes hypertension, and hypocalciuria and hypomagnesaemia are not features.
C. Liddle syndrome
Liddle syndrome causes hypertension with hypokalaemia, and her pressure is low.
D. Gitelman syndrome (correct)
Correct. Hypocalciuria with hypomagnesaemia, hypokalaemia and alkalosis points to thiazide-like transporter loss.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is D, Gitelman syndrome. Gitelman syndrome is an autosomal recessive loss of function of the thiazide-sensitive Na-Cl cotransporter in the distal tubule.

Why is "Bartter syndrome" not the answer?

Bartter syndrome affects the loop transporter, causes hypercalciuria, and presents in infancy or childhood.

Why is "Primary hyperaldosteronism" not the answer?

Primary hyperaldosteronism causes hypertension, and hypocalciuria and hypomagnesaemia are not features.

Why is "Liddle syndrome" not the answer?

Liddle syndrome causes hypertension with hypokalaemia, and her pressure is low.

What concept does this question test?

It tests Electrolytes: salt-wasting tubulopathy in General Medicine. It mimics chronic thiazide use, with hypokalaemia, metabolic alkalosis, hypomagnesaemia and hypocalciuria, and it presents in adolescence or adulthood with normal or low blood pressure.

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 Electrolytes: salt-wasting tubulopathy?

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.