Clinical biochemistry: central hypothyroidism: practice question

A Biochemistry 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

Biochemistry · Clinical biochemistry: central hypothyroidism

Sample item

A woman who had pituitary surgery has fatigue and cold intolerance. Free T4 is low and TSH is 1.8 mIU/L (reference range 0.4 to 4.0). What does this pattern indicate?

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

The answer and the reasoning

D. Central hypothyroidism from inadequate TSH secretion

In primary hypothyroidism a low free T4 raises TSH through loss of negative feedback. A low free T4 with a normal or low TSH indicates a pituitary or hypothalamic cause, so TSH cannot be used to monitor therapy and free T4 is followed instead. Other pituitary hormones should also be checked.

Option by option

  • A. Thyroid hormone resistance with a raised free T4

    Thyroid hormone resistance has a raised free T4, not a low one.

  • B. Primary hypothyroidism with a compensated thyroid

    Primary disease would raise TSH above the reference range.

  • C. Subclinical hypothyroidism with a mildly raised TSH

    Subclinical hypothyroidism has a raised TSH with a normal free T4.

  • D. Central hypothyroidism from inadequate TSH secretion (correct)

    Correct. A low free T4 with an inappropriately normal TSH indicates a central cause.

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 Biochemistry questions

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Central hypothyroidism from inadequate TSH secretion. In primary hypothyroidism a low free T4 raises TSH through loss of negative feedback.

Why is "Thyroid hormone resistance with a raised free T4" not the answer?

Thyroid hormone resistance has a raised free T4, not a low one.

Why is "Primary hypothyroidism with a compensated thyroid" not the answer?

Primary disease would raise TSH above the reference range.

Why is "Subclinical hypothyroidism with a mildly raised TSH" not the answer?

Subclinical hypothyroidism has a raised TSH with a normal free T4.

What concept does this question test?

It tests Clinical biochemistry: central hypothyroidism in Biochemistry. A low free T4 with a normal or low TSH indicates a pituitary or hypothalamic cause, so TSH cannot be used to monitor therapy and free T4 is followed instead. Other pituitary hormones should also be checked.

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 Clinical biochemistry: central hypothyroidism?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.