Background and Objective: Most patients with
prolactinomas receive pharmacological treatment only, resulting in limited research on the predictors of successful
prolactinoma surgery. In this study, we analyzed whether early postoperative serum
prolactin concentrations and selected
tumor characteristics could predict early, hormonal remission after removal of
prolactinomas. Methods: We prospectively enrolled 48 consecutive patients with
prolactinomas who underwent transsphenoidal resection performed by the same surgeon. Early remission, defined as a lack of
hyperprolactinemia symptoms and normalization of serum
prolactin concentration, was ascertained in all patients at 3 months. We evaluated the invasiveness of
prolactinomas on the Knosp grading scale and measured serum
prolactin concentrations on the first postoperative day. Routine immunohistochemical analysis, evaluation for plurihormonality, and assessment of the Ki-67 proliferation index (<3 or ≥3% of positive nuclei) were performed in all
tumor samples. Results: Of 48 patients, 38 (79%) achieved early biochemical remission at 3 months. Patients in early remission at 3 months had lower serum
prolactin concentrations on the first postoperative day than patients with recurrent or persistent
hyperprolactinemia (p < 0.001). Using univariate logistic regression, larger maximum
tumor diameter (p = 0.014), higher Knosp grade (p < 0.001), and plurihormonality predicted remission at 3 months (p = 0.021). However, using multivariate stepwise logistic regression, only the Knosp grade remained significant (p < 0.001). Conclusions: Radiological assessment of
prolactinoma invasiveness (Knosp grades) and early postoperative serum
prolactin concentrations are important predictors of early remission following transsphenoidal
prolactinoma resection.