However , subgroup analyses for the estrogen dose and the progestin type in relation to changes in SHBG levels did show significant differences : COCs containing second generation progestins and /or the lower estrogen doses ( 20–25 µg EE ) were found to have less impact on SHBG concentrations .
The current literature review and meta- analysis demonstrates that COCs decrease circulating levels of total T and free T and increase SBHG concentrations .
Due to the SHBG increase , free T levels decrease twice as much as total T. The estrogen dose and progestin type of the COC do not influence the decline of total and free T , but both affect SHBG .
BACKGROUND Combined oral contraceptives ( COCs ) reduce levels of and rogen , especially testosterone ( T ) , by inhibiting ovarian and adrenal and rogen synthesis and by increasing levels of sex hormone-binding globulin ( SHBG ) .
Although this suppressive effect has been investigated by numerous studies over many years , to our knowledge no systematic review concerning this issue had been performed .
Associations among oral estrogen use, free testosterone concentration, and lean body mass among postmenopausal women.
Circulating concentrations of sex hormone-binding globulin ( SHBG ) are increased by use of oral estrogen . The objective of this study was to determine whether postmenopausal women who used oral estrogen  had higher serum concentrations of SHBG and lower serum concentrations of free testosterone ( T ) than nonusers , and whether free T was associated with lean body mass , particularly skeletal muscle mass . Subjects were 70 postmenopausal women , 46 - 55 yr old , 46 of whom used oral estrogen .  Total and regional body composition were determined by dual-energy x-ray absorptiometry .  Serum concentrations of SHBG , total T , and estradiol ( E(2 ) ) were determined by RIA .  Free T was calculated from concentrations of total T and SHBG .  Hormone users had higher serum concentrations of E(2 ) and SHBG ( 182.0 + /- 58 . 5 vs. 82.9 + /- 41.1 nmol/L , mean + /- SD , P : < 0.001 ) and lower concentrations of free T ( 3.7 + /- 2.2 vs. 7.9 + /- 4.1 pmol/L , mean + /- SD , P : < 0.001 ) ; total T did not differ . Total lean mass and leg lean mass were significantly correlated with free , but not total T [ r values of 0.29 ( P : < 0.05 ) and 0.31 ( P : < 0.01 ) for total and leg lean mass , respectively , vs. free T ] ; arm lean mass was not correlated with either measure of T. Serum E(2 ) was significantly correlated with SHBG ( r = 0.50 , P : < 0.001 ) and free T ( r = -0.33 , P : < 0.01 ) . These observations imply that , by reducing the concentration of bioavailable T , oral estrogen therapy may accelerate or augment lean mass loss among postmenopausal women . This conclusion awaits confirmation by longitudinal observation
However , subgroup analyses for the estrogen dose and the progestin type in relation to changes in SHBG levels did show significant differences : COCs containing second generation progestins and /or the lower estrogen doses ( 20–25 µg EE ) were found to have less impact on SHBG concentrations .
The current literature review and meta- analysis demonstrates that COCs decrease circulating levels of total T and free T and increase SBHG concentrations .
Due to the SHBG increase , free T levels decrease twice as much as total T. The estrogen dose and progestin type of the COC do not influence the decline of total and free T , but both affect SHBG .
BACKGROUND Combined oral contraceptives ( COCs ) reduce levels of and rogen , especially testosterone ( T ) , by inhibiting ovarian and adrenal and rogen synthesis and by increasing levels of sex hormone-binding globulin ( SHBG ) .
Although this suppressive effect has been investigated by numerous studies over many years , to our knowledge no systematic review concerning this issue had been performed .