Cardiometabolic Risk Factors in Men with Elevated Macroprolactin Content: A Pilot Study

Prolactin-secreting pituitary adenomas: male-specific differences in pathogenesis, clinical presentation and treatment

Prolactinomas (PRLomas) constitute approximately half of all pituitary adenomas and approximately one-fifth of them are diagnosed in males. The clinical presentation of PRLomas results from direct prolactin (PRL) action, duration and severity of hyperprolactinemia, and tumor mass effect. Male PRLomas, compared to females, tend to be larger and more invasive, are associated with higher PRL concentration at diagnosis, present higher proliferative potential, are more frequently resistant to standard pharmacotherapy, and thus may require multimodal approach, including surgical resection, radiotherapy, and alternative medical agents. Therefore, the management of PRLomas in men is challenging in many cases. Additionally, hyperprolactinemia is associated with a significant negative impact on men's health, including sexual function and fertility potential, bone health, cardiovascular and metabolic complications, leading to decreased quality of life. In this review, we highlight the differences in pathogenesis, clinical presentation and treatment of PRLomas concerning the male sex.

Comparison of PEG precipitation and ultrafiltration treatment for serum macroprolactin in Chinese patients with hyperprolactinemia

BACKGROUND

Macroprolactinemia is a common cause of hyperprolactinemia (HPRL), with an average worldwide incidence of 18.9 %. This study aimed to explore the feasibility of ultrafiltration (UF) and polyethylene glycol (PEG) precipitation for macroprolactin screening, as well as the incidence and clinical characteristics of Chinese patients with macroprolactinemia.

METHODS

In this study, 94 patients with HPRL and 206 healthy individuals were included. Gel filtration chromatography (GFC), PEG precipitation, and UF were used to screen for macroprolactin, and chemiluminescence was used to determine the prolactin levels.

RESULTS

The detected incidence of macroprolactinemia in the patients with HPRL was 7.45% (7/94, GFC) and 5.32% (5/94, PEG precipitation). Patients with macroprolactinemia usually present with atypical clinical symptoms, moderately increased prolactin levels, and negative or microadenoma-positive pituitary images. In addition, the recovery of monomeric prolactin by PEG precipitation and UF was significantly correlated to that of GFC (r _PEG=0.493, P<0.001; r _UF=0.226, P=0.014), with a higher correlation coefficient between PEG precipitation and GFC. Furthermore, PEG precipitation had a smaller variation (95% confidence interval [CI]: -35.77% to 18.34%) than UF in monomeric prolactin recovery and substantial diagnostic consistency with GFC (Cohen's kappa coefficient=0.647). The proportion of monomeric prolactin in patients with HPRL did not change significantly between the two visits within one year (P >0.05).

CONCLUSION

The incidence of macroprolactinemia in Chinese patients with HPRL is low in the present study. Based on our analysis, we recommend that only patients who are clinically suspected of having macroprolactinemia should be screened using PEG precipitation.

The interplay between prolactin and cardiovascular disease

Hyperprolactinemia can be caused by several conditions and its effects on the hypothalamic-pituitary-gonadal axis are understood in more detail. Nevertheless, in recent decades, other metabolic effects have been studied and data pointed to a potential increased cardiovascular disease (CVD) risk. A recent study showed a decrease in total and LDL- cholesterol only in men with prolactinoma treated with dopamine agonists (DA) supporting the previous results of a population study with increased CVD risk in men harboring prolactinoma. However, other population studies did not find a correlation between prolactin (PRL) levels and CVD risk or mortality. There is also data pointing to an increase in high-density lipoprotein levels, and decreases in triglycerides, carotid-intima-media thickness, C-reactive protein, and homocysteine levels in patients with prolactinoma on DA treatment. PRL was also implicated in endothelial dysfunction in pre and postmenopausal women. Withdrawal of DA resulted in negative changes in vascular parameters and an increase in plasma fibrinogen. It has been shown that PRL levels were positively correlated with blood pressure and inversely correlated with dilatation of the brachial artery and insulin sensitivity, increased homocysteine levels, and elevated D-dimer levels. Regarding possible mechanisms for the association between hyperprolactinemia and CVD risk, they include a possible direct effect of PRL, hypogonadism, and even effects of DA treatment, independently of changes in PRL levels. In conclusion, hyperprolactinemia seems to be associated with impaired endothelial function and DA treatment could improve CVD risk. More studies evaluating CVD risk in hyperprolactinemic patients are important to define a potential indication of treatment beyond hypogonadism.