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

Abstract

Background Macroprolactinemia is a condition associated with the presence of large amounts of high molecular weight complexes of prolactin. Despite high prevalence, clinical significance of macroprolactin remains poorly understood. Objective The aim of this study was to assess cardiometabolic risk in men with isolated macroprolactinemia. Methods The study population included 11 men with isolated macroprolactinemia, 14 subjects with monomeric hyperprolactinemia and 14 men with prolactin levels within the reference range. Glucose homeostasis markers, plasma lipids, as well as plasma levels of uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine and 25-hydroxyvitamin D were determined in all included patients. Results Compared to healthy counterparts, men with isolated macroprolactinemia had higher levels of 2-h postchallenge glucose, hsCRP and fibrinogen, lower levels of 25-hydroxyvitamin D and reduced insulin sensitivity. Patients with monomeric hyperprolactinemia were characterized by increased plasma levels of 2-h postchallenge glucose, triglycerides, uric acid, hsCRP, fibrinogen and homocysteine, reduced insulin sensitivity and decreased plasma concentrations of HDL cholesterol and 25-hydroxyvitamin D. Subjects with isolated macroprolactinemia differed from patients with monomeric hyperprolactinemia in postchallenge plasma glucose, insulin sensitivity, uric acid, hsCRP, fibrinogen, homocysteine and 25-hydroxyvitamin D. In men with monomeric hyperprolactinemia, uric acid, hsCRP, fibrinogen, homocysteine and 25-hydroxyvitamin D, while in men with elevated levels of macroprolactin, uric acid, hsCRP, fibrinogen and 25-hydroxyvitamin D correlated with a content of monomeric prolactin or macroprolactin, respectively, as well as with a degree of insulin sensitivity. Conclusions The obtained results suggest that macroprolactinemia may increase cardiometabolic risk but to a lesser extent than monomeric hyperprolactinemia.

Macroprolactinaemia modulates cardiometabolic effects of fenofibrate in men with atherogenic dyslipidaemia: A pilot study

“…In line with our recent research, including a younger population of men, male subjects with macroprolactinaemia had higher concentrations of hsCRP and fibrinogen, and lower concentrations of 25‐hydroxyvitamin D, as well as were more insulin‐resistant than subjects with normal prolactin levels. The study protocol used in the present study allowed us to minimize the association of the obtained results with the impact of age, body mass, blood pressure and plasma lipids, all of which were similar between the groups.…”

“…These unfavourable cardiometabolic properties of macroprolactin may be explained either by its ability to dissociate from complexes of macroprolactin with immunoglobulins (mainly with immunoglobulin G) with the release of small amounts of monomeric hormone or to some direct stimulatory effect of macroprolactin on peripheral prolactin receptors. In line with these explanations, the impact of macroprolactinaemia on the assessed biomarkers was less pronounced than that of monomeric hyperprolactinaemia, the presence of which was associated in our earlier reports with pronounced and multidirectional changes in all measured cardiometabolic risk factors (uric acid, hsCRP, homocysteine, fibrinogen and HOMA1‐IR).…”

“…Moreover, in subjects with diabetes, glycated haemoglobulin levels were higher in case of coexisting macroprolactinaemia . Finally, macroprolactinaemia was found to increase cardiometabolic risk but to a lesser extent than monomeric hyperprolactinaemia . These finding may suggest that elevated levels of macroprolactin mimic the action of monomeric prolactin.…”

Macroprolactinemia Attenuates the Impact of Levothyroxine on Hypothalamic‐Pituitary‐Thyroid Axis Activity and Thyroid Autoimmunity in Women With Autoimmune Hypothyroidism

“…In line with our previous studies including subjects without thyroid dysfunction, 10,11,17 the presence of macroprolactinemia in women with subclinical autoimmune hypothyroidism was associated with decreased levels of 25‐hydroxyvitamin D. Although autoimmune thyroid diseases are characterized by low vitamin D status, 18,19 while exogenous cholecalciferol reduced thyroid antibody titers, 20 similar baseline titers of TPOAb and TgAb exclude the possible association of the obtained results with differences in the severity of autoimmune thyroiditis in both treatment arms. It is difficult to explain the mechanism underlying reduced 25‐hydroxyvitamin D levels in women with macroprolactinemia.…”

“…Subjects with diabetes and elevated levels of big‐big prolactin were characterized by higher values of glycated hemoglobin than their counterparts with diabetes and prolactin levels within the reference range 9 . Irrespective of sex, the presence of macroprolactinemia increased circulating levels of cardiometabolic risk factors, 10,11 as well as impaired lipid‐lowering and pleiotropic effects of statins and fibrates 12,13 …”