Prolactin is associated with metabolic risk and cortisol in 1007 women with polycystic ovary syndrome

Abstract

Study question: Is there an association between prolactin and markers of metabolic risk in polycystic ovary syndrome (PCOS)? Summary answer: Low serum prolactin was a metabolic risk marker in PCOS. What is known already: Prolactin is routinely measured to exclude endocrine diseases in PCOS. Recent studies have suggested that prolactin can be used as a marker for metabolic and cardiovascular risk. Study design, size, duration: Retrospective cross-sectional study in an academic tertiary-care medical center. Datawere collected during 1997-2012. Premenopausal women (n = 1007) with hirsutism and/or PCOS and 116 healthy, age-matched controlswere included. Prolactin levels were measured in blood samples taken in the morning after a minimum of 2 h awakening time. Macroprolactinemia was excluded by the precipitation of serum with polyethylene glycol in patients with increased prolactin levels. Participants/materials, setting, methods: Serum prolactin levels were measured along with a clinical evaluation (Ferriman-Gallwey score, BMI, waist circumference, blood pressure) plus hormone analyses (sex hormones, fasting lipids, insulin, glucose), transvaginal ultrasound, and oral glucose tolerance (n = 234) and adrenocorticotrophic hormone tests (n = 201). All patients had prolactin levels below the upper reference limit (23 mg/l). Main results and the role of chance: Prolactin levels were significantly lower in patients versus controls; median (quartiles) prolactin levels 7 (5-10) versus 9 (7-13) mg/l (P < 0.001). In the patient population prolactin levels were inversely associated with age, smoking status, waist circumference, total cholesterol, triglyceride and low-density lipoprotein (LDL) and positively associated with high-density lipoprotein, estradiol, total testosterone, dehydroepiandrosterone sulfate, 17-hydroxyprogesterone and cortisol levels. In multiple regression analyses, prolactinwas inversely associated with LDL and positively associated with estradiol, 17-hydroxyprogesterone and cortisol after correcting for age, BMI and smoking status in patients with PCOS. Limitations, reasons for caution: The study design was cross-sectional and prospective studies are needed to further determine the impact of prolactin levels on cardiovascular outcomes. Patients included in the study were relatively lean and only 20 had diabetes, which could have affected our findings. In addition, the collection of blood samples when estrogen levels were low (follicular phase) could be related to the lower levels of prolactin. Furthermore, as prolactin is secreted in a pulsatile manner, several measures of prolactin may be needed to further investigate associations between prolactin and metabolic risk. Wider implications of thefindings: Ourfindings of inverse associations between prolactin levels and metabolic risk markers are supported by studies in populations ofwomenwithoutPCOS. The association between prolactin and adrenal activity should be evaluated in future studies. © The Author 2014.