Question:hard
Which level of prolactin definitely suggests a prolactinoma?
Which level of prolactin definitely suggests a prolactinoma?
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Only a prolactin clearly above 200 ng/ml is diagnostic of a prolactinoma.
Updated On: Jun 24, 2026
- 300 ng/ml
- 150 ng/ml
- 200 ng/ml
- 100 ng/ml
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Recognise that prolactin can rise modestly from medications, hypothyroidism or pituitary stalk compression, so a small bump is non-specific. Step 2: The question asks for the level that definitely (not just possibly) indicates a prolactin-secreting adenoma. Step 3: Clinically a value sustained above about $150$ to $200\ ng/ml$ is regarded as confirmatory for a prolactinoma; of the listed figures, $200\ ng/ml$ clears this threshold. Step 4: The lower values of 50 and 100 ng/ml overlap with benign secondary causes and cannot definitely confirm the tumour, so the diagnostic level is 200 ng/ml.\[\boxed{\text{200 ng/ml}}\]
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