PRELIMINARY STUDY Serum Leptin Levels and Hypertension in Iranian Obese Children Maryam Ghodsi, MD, Hossein Fakhrzadeh, MD, Alireza Moayyeri, MD, Anahita Hamidi, MD, Pantea Ebrahimpour, MD, and Bagher Larijani, MD Abstract: Primary hypertension in children has become common with the rise in prevalence of childhood obesity. The mechanisms underlying obesity-induced high blood pressure are unclear. Leptin is known to play a role in the pathophysiology of obesity. We examined obese children to look for a relationship between leptin and blood pressure. Children from all the primary schools of the 6th region of Tehran were screened for obesity. Anthropometric mea- surements were done, and blood samples for the measurement of serum leptin were collected from 515 obese children. Children were divided into normotensive and hypertensive groups and serum leptin levels were compared. The median serum leptin level for all obese children was 9.80 ng/mL (5.00 –14.40 ng/mL). There was no sig- nificant difference in leptin levels between hypertensive and normo- tensive groups. In both groups, serum leptin levels were significantly correlated with body mass index (BMI) and systolic, but not dia- stolic, blood pressure. In the multivariate linear regression model constructed by age, sex, BMI, and leptin as independent variables, leptin was not an independent predictor of systolic or diastolic blood pressure. Although leptin was correlated with blood pressure in a univariate analysis, it lost its predictive power after adjustment for other important variables, especially BMI. It seems unlikely that plasma leptin is a mediator of hypertension in obese children. Key Words: leptin, obesity, adipocytokine, childhood, hypertension, Iran (The Endocrinologist 2007;17: 258 –261) T he negative health effects of obesity include diabetes mellitus, heart disease, osteoarthritis, the metabolic syn- drome, and psychosocial effects. 1 Hypertension is a major cause of cardiovascular morbidity and mortality. 2 Essential hypertension in adults is thought to be a process that begins in childhood 3,4 and has become an important medical prob- lem in children and adolescents. 5 Obese children are at a higher risk for hypertension than nonobese children. 6 There are many studies suggesting an association between obesity and hypertension. 7–9 The pathophysiologic mechanisms for the development of obesity- induced hypertension are unclear. Leptin, an adipocytokine secreted from adipose tissue, is thought to play a role in the pathophysiology of obesity. 10 Higher serum leptin concentrations are found in obese subjects compared with normal or lean individuals. 11,12 Body fat mass correlates positively with serum leptin levels in all ages. 13–16 Several animal studies have suggested that leptin raises blood pressure via sympathetic nervous system activation. 17–19 Human studies, however, are less consistent. For instance, Agata et al reported higher serum leptin levels in hypertensive men compared with normotensive men. 20 Suter et al 21 reported a significant relationship between systolic blood pressure and plasma leptin levels in hypertensive women but not in hyper- tensive men. Kokot et al 22 found no difference in plasma leptin levels between hypertensive patients and normal subjects. Few studies on this issue have been conducted in children. 23,24 We conducted this study to look for such a relationship between leptin and blood pressure in obese children. MATERIALS AND METHODS This study was conducted between January and May of 2004. All primary school children in the 6th district of Tehran were screened for obesity. The children with waist circum- ferences equal to or above 61 cm were invited to attend an outpatient clinic. 25 Of the 563 pupils who attended the clinic, 515 (aged 7–12; 264 boys) were found to be obese according to Hosseini et al 26 and were included in the study. The study was approved by the Ethics Committee of Tehran University of Medical Science. Written informed consents were obtained from parents before entering their children into the study. Anthropometric measurements were done in the clinic. All instruments were standardized and calibrated before the examination. Body weight was recorded using a standard beam balance scale, with subjects barefoot and wearing light dresses. Weights were rounded off to the nearest 0.5 kg. Heights were recorded to the nearest 0.5 cm using a stadi- ometer. The children were barefoot, heels together, and head touching the ruler with line of sight aligned horizontally. Body mass index (BMI) was calculated as the ratio of body weight (in kilograms) to body height (in meters) squared. From the Endocrinology and Metabolism Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. This study was supported by an internal grant from Endocrinology and Metabolism Research Center. Reprints: Bagher Larijani, Endocrinology and Metabolism Research Center, Shariati Hospital, Northern Kargar Ave., Tehran 14114, Iran. E-mail: emrc@sina.tums.ac.ir. Copyright © 2007 by Lippincott Williams & Wilkins ISSN: 1051-2144/07/1705-0258 DOI: 10.1097/TEN.0b013e3181578691 The Endocrinologist • Volume 17, Number 5, October 2007 258