An ultrarapid prognostic index in microprolactinoma surgery

Object. Prolactinomas account for approximately 40% of pituitary tumors. If the tumor does not exceed 10 mm at its largest diameter (microprolactinoma ), the chances of definitive cure as a result of surgery alone vary from 62 to 89% depending on the series. Until now, however, there was no mechanism to predict whether total excision of a tumor had been accomplished. To imp rove the chances of total excision, we compared the peri- and postoperative kinetics of circulating prolactin (PRL) in patients judged to be cured and those not cured. Methods. The pre-, peri-, and postoperative variations in blood PRL concent rations were determined using assays conducted at 10-minute intervals. Of t he 36 patients included in the study, 27 were considered cured (resumption of a normal menstrual cycle within 6 months, PRL concentration at 9 days [m ean +/- standard deviation 2.5 +/- 2.1 ng/ml] and 12 months [4.5 +/- 2.2 ng /ml] after the operation < 10 ng/ml and normally stimulated by metocloprami de and thyrotropin-releasing hormone [TRH]). Nine patients were not cured ( PRL 20 +/- 15.7 ng/ml at 9 days after surgery, with no response to metoclop ramide and TRH). The kinetics of PRL decrease in definitively cured patient s were characterized by the following: 1) the initial slope of the curve de creased by at least 11% within the first 10 minutes after resection, and 2) immediate postoperative PRL concentrations were 20 ng/ml or less. Conclusions. The measurement of the kinetics of PRL decrease during surgery allows the chance of gross-total resection to be successfully predicted le ss than 25 minutes after excision of the adenoma. Provided an ultrarapid as say is available (the test used in the present study took < 15 minutes), th is prognostic index would be useful to make a decision to continue the surg ical procedure when the initial PRL slope is judged to be insufficient. Its use may also be extended to other pituitary tumors such as somatotropic ad enoma and basophilic adenoma (Cushing's disease).