Defining postoperative values for successful resection of prolactinomas

We, as other authors, have noted that late relapse of hyperprolactinemia following apparent successful adenomectomy in women harboring microprolactinomas is not rare.[1-3] On retrospective review of a series of tumors treated at the University of Southern California teaching hospitals, we have found that the immediate postoperative prolactin level may be predictive of late recurrence of hyperprolactinemia.[4] It is our routine to ascertain prolactin levels at 3 days and 6 weeks postoperatively. Of 133 patients undergoing microadenomectomy who had 3-day postoperative prolactin levels of less than 10 μg/L (the vast majority of these were less than 3 μg/L), 132 or 99% had prolactin levels of less than 20 μg/L at their 6-week follow-up examination. At 5 years postoperatively, 130 (98%) of the original 133 patients still had normal prolactin levels. However, of 43 patients who had 3-day postoperative prolactin levels in the range of 10 to 20 μg/L, only 32 (74%) had prolactin levels in the normal range at 6 weeks postoperatively, and only five (16%) of this group of 32 patients had normal prolactin levels at 5-year follow-up review. Therefore, although 18% of patients who have a normal postoperative prolactin level at 6 weeks will develop recurrent hyperprolactinemia when followed for 5 years, only three (7%) of 41 represent patients with immediate prolactin levels of less than 10 μg/L, whereas the remainder were in the group with immediate postoperative prolactin levels in the 10 to 20 μg/L range.