Hyperprolactinemia has no effect on plasma ghrelin levels in patients with prolactinoma

Accumulating evidence suggests that prolactin is a modulator of body weight and composition and that it regulates some transporters in adipose tissue. It was demonstrated that hyperprolactinemia is associated with weight gain and obesity. Ghrelin is a novel hormone secreted from many organs including the pituitary gland. Ghrelin acts by regulating energy homeostasis and stimulating appetite. The aim of this study is to investigate whether ghrelin has a role in the case of weight gain in patients with prolactinoma.

Forty-four patients with prolactinoma, both newly diagnosed and undergoing cabergoline treatment, were included in this study. Age- and sex-matched healthy subjects were included in the control group. Serum fasting glucose, insulin, lipid profile, and ghrelin levels were measured. Homeostasis model assessment of insulin resistance (HOMA-IR) was also calculated. Body mass index (BMI) and total fat ratio (%) of all the participants were assessed by bioelectrical impedance analysis using TBF-310GS™ (Tanita Corporation, Tokyo, Japan).

Patients with prolactinoma demonstrated significantly higher serum levels of fasting insulin, triglyceride, and waist and hip circumference measurement. No significant difference was found between the fasting glucose, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and HOMA-IR levels. BMI was significantly higher in the patients with prolactinoma than that in the control group (p<0.05). Additionally, the total body fat percentage was higher in the patients with prolactinoma than that in the control group; however, the difference was not significant (p>0.05). Furthermore, there was no significant difference in terms of the ghrelin levels between these groups. There was a correlation with serum ghrelin and growth hormone levels (p<0.02, rho=0.489). However, no significant correlation was obtained between serum prolactin or ghrelin levels and body fat percentage.

According to the results of our study, ghrelin has no effect on weight gain in patients with prolactinoma. Further studies are needed to evaluate whether ghrelin affects the prevalence of obesity in patients with prolactinoma.