Increased risk for venous thrombembolism in patients with prolactinomas

Objective: In a previous study we demonstrated that hyperprolactinemia causes increased ADP stimulation of platelets both in vitro and in vivo. Moreover, we showed a higher incidence of venous thrombembolism (VTE) in patients with medical treated prolactinomas compared to the general population.

Material and Methods: In attempt to analyse the association between pituitary tumor especially PRL-secreting pituitary adenomas and VTE we investigated 311 patients undergoing pituitary surgery. Diagnosis based on immunohistochemistry and hormonal findings. Hormone active adenomas (n=27 GH- and n=75 PRL- secreting) and non-functioning pituitary tumors (n=209) were analysed.

Results: In patients with non-functioning tumors we detected 6 (2.9%) prae- and 1 (0.5%) postoperative VTE, whereas GH-adenoma showed 1 VTE (3.7%) praeoperative. However, patients with prolactinomas showed a significant (p<0.001) higher incidence of prae- n=5 (6.7%) and postoperative n=5 (6.7%) VTE than found in patients with non-functioning-adenomas, GH-secreting adenomas or among the general population.

Conclusions: Our study indicates that patients with pituitary tumors especially with prolactinomas seem to have an increased risk for VTE. One of the reasons of this increased risk might be the thrombogenic effect of hyperprolactinemia mediated through enhanced platelet reactivity.