open access

Vol 56, No 6 (2005)
Original papers
Published online: 2006-06-26
Submitted: 2013-02-15
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Age, insulin, SHBG and sex steroids exert secondary influence on plasma leptin level in women

Tomasz Milewicz, Józef Krzysiek, Agnieszka Janczak-Saif, Krystyna Sztefko, Magdalena
Endokrynologia Polska 2005;56(6):883-890.

open access

Vol 56, No 6 (2005)
Original papers
Published online: 2006-06-26
Submitted: 2013-02-15

Abstract

Aim. As the link between body fat and leptin is well known, the aim of the study was to seek for secondary regulators of plasma leptin level. Patients. 86 women (mean: age 47.0±14.3 years; estradiol 50.0±60.6 ng/l; FSH 52.4±42.9 IU/l; BMI 26.9±5.9) divided into three groups according to their BMI. Group A: 39 normal weight women (mean: age 44.4±16.0 years; estradiol 69.6±79.8 ng/l; FSH 50.4±47.7 IU/l; BMI 22.9±1.3). Group B: 27 overweighted women (mean: age 55.0±6.4 years; estradiol 25.1±17.2 ng/l; FSH 75.6±26.3 IU/l; BMI 27.7±1.6). Group C: 21 obese women with mean: age 48.7±12.2 years; estradiol 36.9±44.0 ng/l; FSH 42.3±36.6 IU/l and BMI 34.6±4.9.
Methods. Standard clinical evaluation and hormone evaluation (LH, FSH, prolactin, estradiol, leptin, insulin-like growth factor-I (IGF-I), human growth hormone (hGH), insulin-like growth factor binding protein-3 (IGFBP-3), insulin, dihydroepiandrosterone sulphate (DHEAS), sex hormone binding globin (SHBG) and testosterone were done in basic condition which levels of were measured by RIA kits.
Statistical analysis. Shapiro-Wilk test, Mann-Whitney-Wilcoxon u test, Spearman rank correlation coefficient and stepwise multiple regression: p values of 0.05 or less were considered as significant.
Results. Taking all women into account (n=86) the plasma leptin level correlated directly with age (r=0.32; p<0.02), body mass (r=0.60; p<0.001), BMI (r=0.71; p<0.001) as well as inversely with estradiol (r=-0.21; p<0.05), IGF-I (r=-0.24; p<0.05), SHBG (r=-0.34; p<0.01) and DHEAS (r=-0.30; p<0.01). However only in the group B leptin/age relation remained (r=0.40; p<0.05) after the division according to BMI. In the group B the leptin /DHEAS (r=-0.40; p<0.05) and leptin/PRL (r=0.51; p<0.05) links were also present. In the group C the leptin/SHGB relation (r=-0.56; p<0.02) only remained and an association between insulin and leptin was found (r=0.48; p<0.05). The body mass and BMI relation to age were again present only in all 86 women (r=0.30; p<0.002: r=0.36; p<0.001 resp.). Having split the women into groups, these links either disappeared or became inverse (rC=-0.39; p<0.05). Taking into consideration age/leptin relation in all women, the division according to the menopausal status revealed the direct relation in premenopausal women (n=29; r=0.43; p<0.02) and a reverse one in postmenopausal women (n=38; r=-0.32; p<0.05). The plasma leptin level was the highest (p<0.001) in group C (23.2&#177;10.4 &#181;g/l) and the lowest was found in the group A (8.9&#177;4.1 &#181;g/l). That corresponded with the differences in mean body mass index and mean body mass. The stepwise multiple regression revealed that body mass index accounted for 31% (p<0.001) and plasma SHBG level accounted for 17.7% (p<0.02) of plasma leptin variance in all women. In the group A body mass and age together accounted for 61% (p<0.01) and estradiol alone accounted for 44% (p<0.02) of plasma leptin variance. In the group B insulin alone accounted for 39% (p<0.05) and together with testosterone accounted for 46% (p<0.05) of plasma leptin variance. Finally in obese women none of the evaluated parameters significantly accounted for leptin variance.
Conclusion. The results presented in this paper confirmed the strong influence of body fat mass on serum leptin concentration. However insulin, SHBG, sex steroids as well as age may also exert secondary influence on plasma leptin level in certain groups of women.

Abstract

Aim. As the link between body fat and leptin is well known, the aim of the study was to seek for secondary regulators of plasma leptin level. Patients. 86 women (mean: age 47.0&#177;14.3 years; estradiol 50.0&#177;60.6 ng/l; FSH 52.4&#177;42.9 IU/l; BMI 26.9&#177;5.9) divided into three groups according to their BMI. Group A: 39 normal weight women (mean: age 44.4&#177;16.0 years; estradiol 69.6&#177;79.8 ng/l; FSH 50.4&#177;47.7 IU/l; BMI 22.9&#177;1.3). Group B: 27 overweighted women (mean: age 55.0&#177;6.4 years; estradiol 25.1&#177;17.2 ng/l; FSH 75.6&#177;26.3 IU/l; BMI 27.7&#177;1.6). Group C: 21 obese women with mean: age 48.7&#177;12.2 years; estradiol 36.9&#177;44.0 ng/l; FSH 42.3&#177;36.6 IU/l and BMI 34.6&#177;4.9.
Methods. Standard clinical evaluation and hormone evaluation (LH, FSH, prolactin, estradiol, leptin, insulin-like growth factor-I (IGF-I), human growth hormone (hGH), insulin-like growth factor binding protein-3 (IGFBP-3), insulin, dihydroepiandrosterone sulphate (DHEAS), sex hormone binding globin (SHBG) and testosterone were done in basic condition which levels of were measured by RIA kits.
Statistical analysis. Shapiro-Wilk test, Mann-Whitney-Wilcoxon u test, Spearman rank correlation coefficient and stepwise multiple regression: p values of 0.05 or less were considered as significant.
Results. Taking all women into account (n=86) the plasma leptin level correlated directly with age (r=0.32; p<0.02), body mass (r=0.60; p<0.001), BMI (r=0.71; p<0.001) as well as inversely with estradiol (r=-0.21; p<0.05), IGF-I (r=-0.24; p<0.05), SHBG (r=-0.34; p<0.01) and DHEAS (r=-0.30; p<0.01). However only in the group B leptin/age relation remained (r=0.40; p<0.05) after the division according to BMI. In the group B the leptin /DHEAS (r=-0.40; p<0.05) and leptin/PRL (r=0.51; p<0.05) links were also present. In the group C the leptin/SHGB relation (r=-0.56; p<0.02) only remained and an association between insulin and leptin was found (r=0.48; p<0.05). The body mass and BMI relation to age were again present only in all 86 women (r=0.30; p<0.002: r=0.36; p<0.001 resp.). Having split the women into groups, these links either disappeared or became inverse (rC=-0.39; p<0.05). Taking into consideration age/leptin relation in all women, the division according to the menopausal status revealed the direct relation in premenopausal women (n=29; r=0.43; p<0.02) and a reverse one in postmenopausal women (n=38; r=-0.32; p<0.05). The plasma leptin level was the highest (p<0.001) in group C (23.2&#177;10.4 &#181;g/l) and the lowest was found in the group A (8.9&#177;4.1 &#181;g/l). That corresponded with the differences in mean body mass index and mean body mass. The stepwise multiple regression revealed that body mass index accounted for 31% (p<0.001) and plasma SHBG level accounted for 17.7% (p<0.02) of plasma leptin variance in all women. In the group A body mass and age together accounted for 61% (p<0.01) and estradiol alone accounted for 44% (p<0.02) of plasma leptin variance. In the group B insulin alone accounted for 39% (p<0.05) and together with testosterone accounted for 46% (p<0.05) of plasma leptin variance. Finally in obese women none of the evaluated parameters significantly accounted for leptin variance.
Conclusion. The results presented in this paper confirmed the strong influence of body fat mass on serum leptin concentration. However insulin, SHBG, sex steroids as well as age may also exert secondary influence on plasma leptin level in certain groups of women.
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Keywords

leptin; age; insulin; SHBG; sex steroids

About this article
Title

Age, insulin, SHBG and sex steroids exert secondary influence on plasma leptin level in women

Journal

Endokrynologia Polska

Issue

Vol 56, No 6 (2005)

Pages

883-890

Published online

2006-06-26

Bibliographic record

Endokrynologia Polska 2005;56(6):883-890.

Keywords

leptin
age
insulin
SHBG
sex steroids

Authors

Tomasz Milewicz
Józef Krzysiek
Agnieszka Janczak-Saif
Krystyna Sztefko
Magdalena

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