Obese Hypertensive Men Have Fasting Serum Concentrations of Leptin Similar to Those of Obese Normotensive Men

BACKGROUND Leptin is a hormone that 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. METHODS We studied 103 obese men (BMI >= 30.0 kg/m2). All men were healthy and were medication-free. We measured blood pressure using 24-h ambulatory blood pressure (ABP) recordings. Hypertension was defined as 24-h systolic ABP >= 130 mm Hg and/or 24-h diastolic ABP >= 80 mm Hg, and normotension was defined as 24-h ABP < 130/80 mm Hg. We measured fasting serum leptin concentrations and used dual-energy X-ray absorptiometry scanning to determine body fat percentage. RESULTS Of the 103 obese men, 64 were hypertensive (24-h systolic ABP-mean +/- standard deviation-137 +/- 11 mg Hg and 24-h diastolic ABP 83 +/- 6 mm Hg) and 40 were normotensive (24-h systolic ABP 117 +/- 6 mg Hg and 24-h diastolic ABP 73 +/- 4 mm Hg). The 2 groups had similar fasting serum leptin concentrations (median-interquartile range; 13.4 (5.7-36.1) <mu>g/L vs. 13.4 (5.4-27.1) mu g/L, P = 0.88) and total fat mass percentage (34.8 +/- 4.5% vs. 34.0 +/- 4.7%, P = 0.90). CONCLUSIONS 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.