Increased risk for venous thrombembolism in patients with non-functional pituitary adenoma

In a previous study we demonstrated that hyperprolactinemia causes increased ADP stimulation of platelets both in vitro and in vivo starting in the upper normal range of prolactin. Moreover, we showed a higher incidence of venous thrombembolism (VTE) in patients with prolactinoma compared to the general population. In attempt to analyse the association between non-functional pituitary adenoma and VTE we compared 182 patients undergoing pituitary surgery and 4122 healthy individuals of a cross sectional study, the Study of Health in Pomerania. The diagnosis of non-functional pituitary adenoma was based on immunohistochemistry and hormonal findings. The frequency of VTE in patients with non-functional pituitary adenoma before surgery and the confounders age, sex, body mass index, smoking, alcohol consumption and diabetes were analysed.

In 16 of the 182 (8.8%) patients with non-functional pituitary adenoma and in 39 of the 4122 (0.9%) controls VTE has been detected. After adjustment for the confounders mentioned above a higher probability of VTE was observed among patients with non-functional pituitary adenoma in comparison to controls (odds ratio: 9.08 95-% confidence interval 4.8–16.9). Moreover, patients with non-functional pituitary adenoma showed significant higher prolactin values than controls (18.9 vs. 7.6 ng/ml; p<0.001).

Therefore, our study might indicate that patients with non-functional pituitary tumors have an increased risk for VTE. One of the reasons of this increased risk might be the thrombogenic effect of prolactin mediated through enhanced platelet reactivity.