Endocrinology: factitious hypoglycaemia: 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: factitious hypoglycaemia

Sample item

A 30-year-old nurse has recurrent episodes of confusion with glucose of 32 mg/dL, relieved by dextrose. During an episode, serum insulin is high, C-peptide is suppressed and the sulfonylurea screen is negative. What is the most likely cause?

ASulfonylurea ingestionBAdrenal insufficiencyCExogenous insulin administrationDInsulinoma

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

The answer and the reasoning

C. Exogenous insulin administration

Endogenous insulin is secreted with C-peptide in equimolar amounts, so an insulinoma or sulfonylurea use gives raised insulin with raised C-peptide and proinsulin. Injected insulin contains no C-peptide and suppresses endogenous production, so insulin is high while C-peptide is low. A person with access to insulin, such as a healthcare worker, fits this pattern.

Option by option

A. Sulfonylurea ingestion
Sulfonylureas stimulate beta cells, so C-peptide would be raised, and the screen is negative.
B. Adrenal insufficiency
Adrenal insufficiency lowers glucose but with appropriately suppressed insulin.
C. Exogenous insulin administration (correct)
High insulin with low C-peptide indicates insulin that is not coming from the pancreas.
D. Insulinoma
An insulinoma gives high insulin, high C-peptide and high proinsulin.

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 C, Exogenous insulin administration. Endogenous insulin is secreted with C-peptide in equimolar amounts, so an insulinoma or sulfonylurea use gives raised insulin with raised C-peptide and proinsulin.

Why is "Sulfonylurea ingestion" not the answer?

Sulfonylureas stimulate beta cells, so C-peptide would be raised, and the screen is negative.

Why is "Adrenal insufficiency" not the answer?

Adrenal insufficiency lowers glucose but with appropriately suppressed insulin.

Why is "Insulinoma" not the answer?

An insulinoma gives high insulin, high C-peptide and high proinsulin.

What concept does this question test?

It tests Endocrinology: factitious hypoglycaemia in General Medicine. Injected insulin contains no C-peptide and suppresses endogenous production, so insulin is high while C-peptide is low. A person with access to insulin, such as a healthcare worker, fits this pattern.

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: factitious hypoglycaemia?

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.