BIOSCIENCES BIOTECHNOLOGY RESEARCH ASIA, December 2011. Vol. 8(2), p. 885-891 * To whom all correspondence should be addressed. E-mail: aswarsy@ksu.edu.sa Plasma Leptin and its Correlation with Anthropometric Variables in the Saudi Population Arjumand S. Warsy*, Nashwa Othman¹, Maha Saleh Alsulaimani*, Zeinab Habib², Mona Halawani³, Mohammad Addar², Sooad Al-Daihan*, Abeer Al-Dbass and Mohammad Al Anazi *Department of Biochemistry, College of Science; ¹Central Laboratory, Center for Science and Medical Studies for Girls, ²Department of Ob/Gyn., ³Department of Dermatology, College of Medicine, King Saud University King Saud University, Riyadh, (Saudi Arabia). (Received: 12 November 2011; accepted: 27 December 2011) Leptin, a 16 kDa non-glycosylated polypeptide also referred to as obesity hormone, is a product of the LEP gene and is mainly secreted by adipose tissue having a role in regulating food intake and energy expenditure. The levels of leptin in the body are an indication of the body fat stores. Studies have shown ethnic variations in leptin levels in different populations. The aim of this study was to determine the levels of leptin in Saudi males and females and to analyze the effect of weight changes on leptin levels. We investigated 31 healthy Saudi males and 168 females. The ages, weight, height and BMI were recorded into specially designed forms and leptin levels were estimated using radioimmunoassay methods (Linco Research USA). The mean ± SD for leptin in Saudi males was found to be 11.95 + 7.22 ng/ml and for females was 16.4 ± 7. ng/ml which are significantly higher than those reported from other populations. Statistically significant positive correlations of leptin levels were found with age, weight and BMI in both males and females. The results indicate that leptin levels increase with an increase in age and BMI suggesting that most obese persons are insensitive to endogenous leptin production, in hence controlling their weight. Key words : Leptin, Saudi Arabia, age, gender, Body Mass Index. Leptin, a 16 kDa non-glycosylated polypeptide also referred to as the obesity hormone, is a adipose tissue peptide hormone, which plays an important role in the regulation of body fat and is the product of the LEP gene 1,2 . First it was thought that this hormone is produced only by adipocytes and is involved only in modulating satiety and energy homeostasis 2,3,4 but, now it is known to be produced in many tissues and is also associated with the advent of reproductive maturity and fertility 5,6 , neuroendocrine function 7 angiogenesis 8, 9 , bone formation 10 . It acts centrally to regulates food intake and energy expenditure 11 , and mediates it’s action through its functional long form receptor (OB-Rb; LRb) in the hypothalamus 12,13,14 . Leptin regulates body weight through inhibiting food intake and