Serum @entity1243 concentrations are highly correlated with body @entity1386 , but there is considerable variability among individuals after adjusting for differences in body @entity1386 . Theoretically, sex hormone levels may influence serum @entity1243 , since the levels are higher in @entity1 than in @entity1 independently of body fat. Increasing old age is associated with decreases in serum sex hormone concentrations and changes in body @entity1386 that may independently alter serum @entity1243 concentrations. In a cross-sectional sample of 106 @entity1 and 166 @entity1 aged 62 to 98 years, serum @entity1243 adjusted for total body fat had a significant positive association with age in @entity1 and a nonsignificant negative association with age in women. Serum @entity251 had a significant negative association with serum @entity1243 in @entity1 after adjusting for total body fat, the fasting insulin resistance index (FIRI), and @entity443 ( @entity443 ). In a longitudinal sample of 22 elderly @entity1 and 52 women, serum @entity1243 levels increased significantly over a 14-year period in @entity1 , but not in @entity1 . Increases in serum @entity1243 were significantly associated with decreases in serum @entity251 but not with changes in the body mass index (BMI) in @entity1 . In contrast, changes in @entity1243 were associated with changes in the BMI but not with changes in serum @entity1815 in @entity1 . These results suggest that differences among @entity1 and changes with age in serum @entity1243 are associated with circulating levels of @entity251 . Elderly @entity1 become progressively "hyperleptinemic" with age regardless of changes in body @entity1386 , possibly due to decreasing @entity251 levels.

Age-related changes in sex hormones affect the sex difference in serum XXXX independently of changes in body fat.

@entity1 :: ('9606', 'Species') :: ['women', 'men'] @entity251 :: ('MESH:D013739', 'Chemical') :: ['testosterone'] @entity1243 :: ('3952', 'Gene') :: ['leptin'] @entity1815 :: ('MESH:D004970', 'Chemical') :: ['estrone'] @entity1386 :: ('MESH:D018205', 'Disease') :: ['fatness'] @entity443 :: ('6462', 'Gene') :: ['sex hormone-binding globulin', 'SHBG']
@entity1243 :: (3952,Gene) :: ['leptin']
