Endocrinology: 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 · Endocrinology

Sample item

A man passes large volumes of dilute urine. During a water deprivation test the urine stays dilute, but after desmopressin the urine osmolality rises markedly. What is the diagnosis?

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

The answer and the reasoning

A. Central diabetes insipidus

In central diabetes insipidus the pituitary does not release antidiuretic hormone, so urine stays dilute with water deprivation but concentrates once the hormone analogue is given. In nephrogenic disease the kidney does not respond even to desmopressin. In primary polydipsia the urine concentrates with water deprivation.

Option by option

  • A. Central diabetes insipidus (correct)

    Correct. A response to desmopressin shows the kidney can respond, so the deficit is of hormone.

  • B. Nephrogenic diabetes insipidus

    In nephrogenic disease the urine remains dilute even after desmopressin.

  • C. Primary polydipsia

    Primary polydipsia concentrates the urine during water deprivation.

  • D. Diabetes mellitus

    Diabetes mellitus produces glycosuria with high urine osmolality and would be identified by high blood glucose.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Central diabetes insipidus. In central diabetes insipidus the pituitary does not release antidiuretic hormone, so urine stays dilute with water deprivation but concentrates once the hormone analogue is given.

Why is "Nephrogenic diabetes insipidus" not the answer?

In nephrogenic disease the urine remains dilute even after desmopressin.

Why is "Primary polydipsia" not the answer?

Primary polydipsia concentrates the urine during water deprivation.

Why is "Diabetes mellitus" not the answer?

Diabetes mellitus produces glycosuria with high urine osmolality and would be identified by high blood glucose.

What concept does this question test?

It tests Endocrinology in General Medicine. In nephrogenic disease the kidney does not respond even to desmopressin. In primary polydipsia the urine concentrates with water deprivation.

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 Endocrinology?

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.