Endocrine Abstracts

Hyperprolactinaemia in association with a large sellar lesion could represent either tumoural secretion of prolactin (PRL) or stalk disruption by a non-prolactinoma: the differentiation has important therapeutic consequences. We have previously shown that based on currently used assays disconnection hyperprolactinaemia associated with non-functioning adenoma (NFA) practically never exceeds levels above 2000 mU/l. We aimed to verify our proposed disconnection hyperprolactinaemia levels by investigating the pre-operative serum PRL of all patients presenting to our Department between 1/1990–6/2011 with histologically verified non-adenomatous sellar/parasellar lesions showing suprasellar extension. Patients were identified from our database (audit registration no 1978). Information on PRL, medications and conditions capable of increasing PRL was collected. 110 subjects were finally included (median age 46.5 years, range 17–78; 47 males). 25 were on medications capable of increasing PRL. The median serum PRL in the total group was 272 mU/L (range 37–6050) [males: median 247 mU/L (51–1136) - females: median 277 mU/L (37–6050)]. Hyperprolactinaemia was found in 26.4% (29/110). PRL exceeding 2000 mU/L was found in 1.8% (2/110). Only a single patient of the 85 (1.2%) not taking medications capable of elevating serum PRL had a value above 2000 mU/l. This is the first study systematically evaluating disconnection hyperpolactinaemia associated with non-adenomatous sellar/parasellar lesions. The results are in accord with our previously published data on NFAs verifying that with the assays used, disruption of the dopaminergic inhibition by mass effect only extremely rarely can lead to values of PRL above 2000 mU/l; hyperprolactinaemia above this limit in the absence of relevant medications is virtually always attributable to autonomous PRL secretion by an adenoma.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.