The prevalence of silent acromegaly in prolactinomas is very low

Purpose The aim of this study was to evaluate the somatotroph axis in a large series of patients with prolactinoma to verify the prevalence of silent acromegaly in this population. Methods A hundred and forty-four patients were enrolled in a multicenter study: 90 were already on cabergoline (CAB) and enrolled in a cross-sectional arm (group A) with random PRL, GH and IGF-I determination on treatment (≥ 3 months), whereas 54 untreated patients were enrolled at diagnosis in a prospective arm (group B) with PRL, GH and IGF-I measurement before and after 6 and 12 months of treatment. In the presence of high IGF-I, CAB was withdrawn for 3 months and GH, IGF-I, PRL and GH during an oral Glucose Tolerance Test (OGTT) were obtained. Results High IGF-I levels (ULN 1.01–1.56) were observed in 9 patients (6.25%, 5F). After CAB withdrawal, IGF-I levels normalized in 5/9 patients, GH was