Leptin is a hormone which is secreted by the adipocytes. In the circulation, leptin levels are directly proportional to the body fat percentage. Studies have shown that higher leptin levels are associated with an increased risk of hypertension after adjusting for body mass index (BMI). Therefore, leptin has been proposed as a mediator of obesity-related hypertension. Whether leptin is associated with hypertension when controlling for body fat percentage remains unclear. We studied 103 obese men (BMI ≥30.0kg/m2). All men were healthy and were medication-free. We measured blood pressure using 24-hour ambulatory blood pressure (ABP) recordings. Hypertension was defined as 24-hour systolic ABP ≥130mm Hg and/or 24-hour diastolic ABP ≥80mm Hg, and normotension was defined as 24-hour ABP <130/80mm Hg. We measured fasting serum leptin concentrations and used dual-energy X-ray absorptiometry scanning to determine body fat percentage. Of the 103 obese men, 64 were hypertensive (24-hour systolic ABP (mean ± standard deviation) 137±11mg Hg and 24-hour diastolic ABP 83±6mm Hg) and 40 were normotensive (24-hour systolic ABP 117±6mg Hg and 24-hour diastolic ABP 73±4mm Hg). The 2 groups had similar fasting serum leptin concentrations (median (interquartile range)) 13.4 (5.7-36.1) µg/L versus 13.4 (5.4-27.1) µg/L, P=0.88) and total fat mass percentage (34.8±4.5% versus 34.0±4.7%, P=0.90). Obese hypertensive men have serum leptin concentrations similar to those of obese normotensive men with comparable body fat percentage measurements. This finding does not support leptin's candidacy as a mediator of obesity-related hypertension.
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