Bravo et al Figure 1 Renal and blood pressure effect of leptin. Adapted from Hall et al 2001. Copyright © 2001. Reproduced with permission from Hall JE, Hildebrandt DA, Kuo J. 2001. Obesity hypertension: role of leptin and sympathetic nervous system. Am J Hypertension, 14(6 Pt 2):103S-115S. 2001; Barba et al 2003; Canatan et al 2004b). Al-Hazimi and Syiamic (2004), for example, found that serum leptin and angiotensin II levels were strong predictors of elevated blood pressure in obese women. Likewise, other investigators (Kunz et al 2000; Golan et al 2002; Canatan et al 2004b) reported higher leptin levels in obese hypertensives compared with obese normotensive individuals, even after controlling for confounders such as age and body mass index (BMI). In another study leptin correlated stronger with systolic and diastolic blood pressure than did with BMI (or waist circumference) in untreated male adults (Barba et al 2003). Moreover, one study found that after a 3-month weight reduction program, leptin continued to correlate positively with mean arterial blood pressure in the hypertensive, but not in the normotensive obese group (Itoh et al 2002). Interestingly, leptin has been found to be elevated in several hypertensive states of pregnancy as well (Anato et al 2000; Vitoratos et al 2001). For instance, Vitoratos et al (2001) reported increased leptin levels in pre-eclamptics compared with normotensive pregnant women of the same gestational age. Of note is also the observation that a positive correlation between leptin and platelet count levels exist in pre-eclamptic women (Anato et al 2000). In disagreement to some of these data, one study found that leptin levels were higher in hypertensives than in 166 Vascular Health and Risk Management 2006:2(2)