Knosp and Hardy Grading Systems are Useful in Predicting Persistence of Male Hypogonadism in Prolactinomas Following Prolactin Normalization

Abstract

Objective: Despite serum prolactin normalization and tumor shrinkage being obtained using dopamine agonist treatment, hypogonadism may persist in several men with prolactinomas. In this study, we evaluated the effects of tumor magnetic resonance imaging features on the persistence of hypogonadism among normoprolactinemic men with prolactinomas objectively using Knosp and Hardy grading systems. Material and Methods: The patients with prolactinomas who achieved serum prolactin normalization using cabergoline therapy were evaluated, respectively. The extent of tumor growth was evaluated on the basis of Knosp and Hardy grading systems both at diagnosis and six months of medical therapy with serum prolactin normalization. Results: A total of 28 cases (18 macro- and 10 microprolactinomas) were included. After six months of treatment with cabergoline, all microprolactinoma patients with hypogonadism at baseline showed recovery (3, 100%). Moreover, nine of 14 macroprolactinoma patients with hypogonadism at inclusion recovered at the end (group 1), and five did not (group 2). Baseline Knosp grades and Hardy numbers did not differ between groups. However, higher Knosp grades and Hardy numbers were observed in patients who consistently had low serum testosterone in the sixth month (group 2) (p=0.01, p=0.02, respectively). All patients in group 2 had invasive tumors (Hardy number III-IV) both at inclusion and the sixth month according to this classification. Conclusion: We demonstrated that macroprolactinomas with persistent hypogonadism despite serum prolactin normalization more commonly showed cavernous sinus invasion and sellar destruction. We proposed that Knosp and Hardy grading systems are useful in predicting the persistence of male hypogonadism in prolactinomas following prolactin normalization.