Beyond normalization: rethinking optimal prolactin levels in prolactinoma management

INTRODUCTION: Prolactinoma, the most common functioning pituitary tumor, poses ongoing challenges due to variable clinical presentation, treatment resistance, and high recurrence rates. While normalization of prolactin (PRL) is a primary therapeutic goal, increasing evidence suggests that both insufficient and excessive PRL suppression may influence long-term outcomes. AREAS COVERED: A narrative literature search of PubMed, Embase, Scopus, Cochrane, and Web of Science was conducted without date restrictions. The review primarily included English-language studies published from 2015 through February 2026, while selected earlier studies were included when they provided essential background context. This review synthesizes current evidence on optimal prolactin levels in prolactinoma management, based on literature from clinical and observational studies. We examine the role of PRL dynamics as a marker of treatment response across pharmacological and surgical approaches. Particular attention is given to predictors of remission, recurrence after dopamine agonist withdrawal, and the clinical implications of both hyper- and hypoprolactinemia. EXPERT OPINION: Lower prolactin levels are associated with improved clinical outcomes; however, excessively low levels do not necessarily indicate optimal therapy and may carry overlooked risks. Early PRL trends reflect tumor response, underscoring the need to define optimal targets for individualized prolactinoma management.