Endocrine Abstracts

Cerebro-spinal fluid (CSF) rhinorrhea is a recognised complication of pituitary surgery, and occasionally occurs following pituitary radiotherapy. Macroprolactinomas (MPRL) may result in spontaneous or dopamine-agonist-induced CSF leaks, however no detailed large comparisons have been made with non-functioning adenomas (NFA). The incidence of this phenomenon and the mechanisms underlying it are not understood.

We have performed a retrospective review of subjects with MPRLs (n=114) seen over a 17-year period (1985–2003), and compared them with a group of subjects with non-functioning pituitary macroadenomas (NFA) (n=180). Our aim was to determine the incidence of spontaneous, and dopamine-agonist-induced rhinorrhea in subjects with MPRLs, and to determine underlying mechanisms.

Spontaneous CSF-rhinorrhea, confirmed by measurement of glucose and beta-transferrin levels, occurred in 3/114 subjects (2.6%) with MPRL; and in a further 7/114 MPRL subjects (6.1%) following dopamine-agonist therapy (1 week-6 months). In contrast no subjects with NFA developed non-surgical rhinorrhea.

We hypothesised that prolactin levels at diagnosis and rate of change of prolactin in response to dopamine-agonists may predict CSF-rhinorrhea. There was no significant difference of mean prolactin at diagnosis between groups; MPRLs with leaks 113306 mU/l or without leaks 122896 mU/l (P>0.2). Furthermore the rate of change of prolactin, assessed using the drop in prolactin per month following at least 3 months of dopamine-agonist therapy was not significantly different between MPRL with leaks 49327 mU/l/month vs. non-leakers 16572 mU/l/month (P=0.07). We also assessed dopamine-agonist resistance, a year following diagnosis, in the two cohorts, and found this to be higher in the leakers than the non-leakers (30% (n=10) vs. 5% (n=104)).

Conclusion: This is the first large series to ascertain the incidence of spontaneous CSF-rhinorrhea in subjects with Macroprolactinoma (9%). This is not a complication of non-functioning pituitary adenomas. Whether the difference in dopamine-agonist resistance is related to the mechanism of prolactinomas inducing CSF-rhinorrhea requires further studies.