598 Obstetrics and Gynecology Board Review •••
❍ Do normal ovulatory menstrual periods occur in women with hyperprolactinemia if they are given
exogenous GnRH?
Yes.
❍ What are the most common tumors associated with delay in pubertal development?
Prolactinomas and craniopharyngiomas.
❍ What is the most common symptom patients report with intrasellar expansion?
Headache.
❍ Can primary hypothyroidism appear similar to a pituitary tumor in imaging studies?
Yes, due to the hypertrophy of the thyrotrophs.
❍ Is galactorrhea more suspicious for malignancy if produced from a single alveolar duct?
Yes.
❍ What is the “hook effect” (when interpreting prolactin levels)?
In the presence of a macroadenoma, markedly elevated prolactin levels (5,000 ng/mL) can appear as mildly
elevated levels (20–200 ng/mL) that is from the hook effect. This occurs because both the capture and signal
antibodies in the sandwich immunoassays are saturated giving an artificially low result.
❍ How would one evaluate for a hook effect when prolactin levels are not as high as expected?
(1) Repeat the test with a 1:1000 serum sample dilution.
OR
(2) Washout can be performed to eliminate excess unbound prolactin after binding to the first antibody.
Microadenoma: Coronal T2W
(Reproduced, with permission, from Dan TD Nguyen, MD. Department of Radiology, Penn State Milton S. Hershey Medical Center.
Hershey, PA.)