P06 - Non gonadal hypopituitarism in prolactinomas: prevalence, predictors and recovery

Abstract Background Prolactinomas account for approximately 50% of all pituitary adenomas. While hypogonadism is a common and expected finding due to the suppressive effect of hyperprolactinemia on the gonadotropic axis, the prevalence and clinical determinants of other pituitary hormone deficiencies in patients with micro- and macroprolactinomas at diagnosis remain poorly characterized. Objective To assess the prevalence of hypopituitarism excluding hypogonadism at diagnosis in patients with prolactinomas, identify clinical and radiological predictors of pituitary dysfunction, and evaluate the recovery of pituitary function during follow- up. Methods We conducted a multicentre retrospective study including 145 patients (98females, 47males) with a confirmed diagnosis of prolactinoma. Results Median tumor size was 9.0 mm (IQR:5.0–19.0), median prolactin level at diagnosis was 168.6 ng/mL (IQR:98.0–470.0), and median follow-up was 70.0 months (IQR:28.3–133.6). At diagnosis, patients with macroprolactinomas had a significantly higher prevalence of hypopituitarism (excluding hypogonadism) compared to those with microprolactinomas (25.8% vs.2.7%, p<0.001). Specifically, macroadenomas were associated with increased rates of secondary adrenal insufficiency (13.6%vs.1.4%,p<0.001), central hypothyroidism (13.6%vs. 1.4%, p<0.001), and growth hormone deficiency (13.6% vs. 1.4%, p<0.001). Stratification by tumor size (<5 mm, 6–9 mm, 10–14 mm, 15–19 mm, >20 mm) revealed a progressive increase in the risk of non-gonadal hypopituitarism, particularly in tumors 15–19mm(17.7%) and >20 mm(38.2%, p<0.001). Factors associated with hypopituitarism at diagnosis included male sex (OR: 5.51, p=0.001), tumor size (OR:1.09, p<0.001), chiasmal/cavernous sinus invasion (OR:1.71, p=0.011), visual field defects (OR: 5.74, p=0.001), and serum prolactin levels (OR:1.00, p=0.001). Multivariable analysis confirmed tumor size as independent predictor (OR:1.11, 95% CI=1.03-1.20, p=0.007). During follow-up, 69.2% of patients with an initial hormone deficiency experienced recovery of at least one pituitary axis. Recovery was more likely in those with smaller tumors (OR: 0.93, p=0.009) and absence of invasive features (OR:0.57, p=0.029). Tumor size was independently associated with hormonal recovery (OR:0.93, 95% CI=0.87-0.99, P=0.045). Conclusion Non-gonadal hypopituitarism is relatively frequent in patients with macroprolactinomas, and its risk increases with tumor size and invasiveness. A significant proportion of patients recover pituitary function during follow-up, particularly those with smaller and non-invasive tumors. Early identification of high- risk patients may support personalized therapeutic strategies.