Age-related changes in sex hormones affect the sex difference in serum leptin independently of changes in body fat.
Serum leptin concentrations are highly correlated with body fatness, but there is considerable variability among individuals after adjusting for differences in body fatness. Theoretically, sex hormone levels may influence serum leptin, since the levels are higher in women than in men independently of body fat. Increasing old age is associated with decreases in serum sex hormone concentrations and changes in body fatness that may independently alter serum leptin concentrations. In a cross-sectional sample of 106 men and 166 women aged 62 to 98 years, serum leptin adjusted for total body fat had a significant positive association with age in men and a nonsignificant negative association with age in women. Serum testosterone had a significant negative association with serum leptin in men after adjusting for total body fat, the fasting insulin resistance index (FIRI), and sex hormone-binding globulin (SHBG). In a longitudinal sample of 22 elderly men and 52 women, serum leptin levels increased significantly over a 14-year period in men, but not in women. Increases in serum leptin were significantly associated with decreases in serum testosterone but not with changes in the body mass index (BMI) in men. In contrast, changes in leptin were associated with changes in the BMI but not with changes in serum estrone in women. These results suggest that differences among men and changes with age in serum leptin are associated with circulating levels of testosterone. Elderly men become progressively "hyperleptinemic" with age regardless of changes in body fatness, possibly due to decreasing testosterone levels.
Baumgartner
R N
RN
Clinical Nutrition Program, School of Medicine, University of New Mexico, Albuquerque 87131, USA.
Waters
D L
DL
Morley
J E
JE
Patrick
P
P
Montoya
G D
GD
Garry
P J
PJ
D000273:Adipose Tissue / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D020738:Leptin; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009516:New Mexico; D011506:Proteins / Q000378:metabolism*; D012737:Sex Factors
D012739:Gonadal Steroid Hormones; D020738:Leptin; D011506:Proteins