Research Article Leptin as well as Free Leptin Receptor Is Associated with Polycystic Ovary Syndrome in Young Women Nasser M. Rizk and Elham Sharif Health Sciences Department, CAS, Qatar University, P.O. Box 2713, Doha, Qatar Correspondence should be addressed to Nasser M. Rizk; nassrizk@qu.edu.qa Received 29 March 2015; Accepted 7 May 2015 Academic Editor: Marek Bolanowski Copyright © 2015 N. M. Rizk and E. Sharif. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background and Aim. Leptin has two forms in the circulation: free and bound forms. Te soluble leptin receptor (sOB-R) circulates in the blood and can bind to leptin. Te aim of this study is to assess the concentrations of the leptin and the sOB-R in PCOS and its relation to adiposity, insulin resistance, and androgens. Methods. A cross-sectional study included 78 female students aged 17–25 years. Fasting serum leptin and sOB-R concentrations were measured. Te anthropometric variables and the hormonal profle such as insulin, female and male sex hormones, and prolactin were assessed. Results. In PCOS, leptin level (ng/ml) and free leptin index (FLI) increased signifcantly while sOB-R (ng/ml) signifcantly decreased compared to control subjects. In age-matched subjects, obese PCOS had increased leptin level in ng/ml (median level with interquartile levels) of 45.67 (41.98–48.04) and decreased sOB-R in ng/ml 11.47 (7.59–16.44) compared to lean PCOS 16.97 (10.60–45.55) for leptin and 16.62 (11.61–17.96) for sOB-R with  values 0.013 and 0.042, respectively. However, body mass index (BMI) is signifcantly correlated with leptin and s-OBR, while no signifcant correlations with parameters of insulin resistance were detected. Conclusion. PCOS is associated with hyperleptinemia and increased free leptin index. Decreased sOB-R could be a compensatory mechanism for the defective action of leptin. 1. Introduction Te prevalence of overweight and obesity increased globally in the previous few decades [1]. Obesity and overweight have a signifcant infuence on reproductive functions in females as the extra body fat may cause problems related to ovulatory dysfunction and infertility [2]. Tis abnormality is frequently associated with the polycystic ovary syndrome (PCOS). Around 4–7% of reproductive-age women have PCOS based upon the National Institute of Health (NIH) criteria [3]. About 30–75% of the patients with PCOS are obese [4] and previous data have reported that 50–60% of patients with PCOS have a central adiposity irrespective of their body mass index (BMI) [5]. Tere is a “complex interaction between obe- sity, insulin and leptin resistance, and the endocrine abnor- malities in PCOS” [6]. Leptin is a product of the ob gene that acts as a sensor to the hypothalamus about the adipose tissue stores as well as a regulator of food intake and the energy balance [7]. A positive relationship between leptin and fat mass and BMI has been reported [8]. Several studies suggested that leptin may be involved in the reproductive axis function at both central and peripheral levels [9, 10]. Amenorrheic athletes have inadequate or low body fat and leptin [11]. Leptin administra- tion in women with hypothalamic amenorrhea improves the reproduction [12]. Leptin afects the hypothalamic secretion of GnRH and gonadotropin secretion [13]. High leptin may interfere with the development of the mature oocyte and may directly activate ovarian 17- hydroxylase enzyme that is involved in ovarian and adrenal steroidogenesis [13]. Leptin in the circulation is present in two main forms: a protein bound and a free form that is the biological active form [14]. Te soluble leptin receptor (sOB-R) circulates in human plasma and is accomplished by binding to leptin and symbolizes the signifcant leptin binding activity in humans [14]. In lean subjects, leptin circulates principally in the bound form while in obesity the leptin circulates mainly as a free form due to small sOB-R concentrations [15]. Te frac- tion of the total leptin concentrations to the sOB-R desig- nates the free leptin index (FLI). Te role of sOB-R in the Hindawi Publishing Corporation International Journal of Endocrinology Volume 2015, Article ID 927805, 10 pages http://dx.doi.org/10.1155/2015/927805