Gender-dependent differences in plasma leptin in essential hypertension

Leptin, the gene product of the ob gene, is influenced by gender and insuli n sensitivity. Because in human hypertension there are important endocrine- hemodynamic gender-dependent differences, we compared plasma leptin in 39 e ssential hypertensives (EH) and in 27 normotensive healthy subjects (HS) ma tched for gender, age, and fat mass. Fat mass was measured by bioelectrical impedance analysis (BIA), plasma lep tin by a sensitive radioimmunoassay RIA (intraassay CV < 6%), and insulin s ensitivity by the HOMA-R index. Both in essential hypertensives and in normotensive subjects plasma leptin was consistently higher in females than in males and was strictly related t o fat mass. Gender differences in plasma leptin were not explained by diffe rences in fat mass. Separate analysis of data by gender showed that leptin was significantly higher (P < .05) in hypertensive men (median, 5.4 ng/mL; interquartile range, 4.1-9.5) than in normotensive men (4.6 ng/mL, 2.6-7.4) whereas it was identical in hypertensive and normotensive women. In essential hypertensives, in a multiple regression model only fat mass, g ender, and the HOMA-R index were independently linked to plasma leptin. Sim ilarly, fat mass and gender were independent predictors of plasma leptin in normotensive subjects. In the combined group of hypertensive and normotensive men, heart rate as w ell as systolic and diastolic pressure were univariate predictors of leptin . However, in a multivariable model only heart rate was independently relat ed to leptin, and neither systolic nor diastolic pressure contributed signi ficantly to explain the variability in plasma leptin. No relationship was f ound between leptin and heart rate or systolic or diastolic pressure in wom en. These results support the notion that leptin may participate in the gender- dependent variability of human hypertension. (C) 2000 American Journal of H ypertension, Ltd.