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 .
Effects of an oral contraceptive containing 30 mcg ethinyl estradiol and 2 mg dienogest on thyroid hormones and androgen parameters: conventional vs. extended-cycle use.
BACKGROUND This study was conducted to investigate the effects of an oral contraceptive containing 30 mcg ethinyl estradiol and 2 mg dienogest on thyroid hormones and and rogen parameters . STUDY DESIGN Thyroid and and rogen parameters were measured in 59 women treated with a monophasic combined oral contraceptive containing 30 mcg ethinyl estradiol and 2 mg dienogest ( EE/DNG ) either conventionally ( 13 cycles with 21 days of treatment+7 days without hormones ) or according to an extended-cycle regimen ( four extended cycles with 84 days of continuous administration of  EE/DNG  , followed by a hormone-free interval of 7 days ) .  Blood sample s were taken on Days 21 - 26 of the preceding control cycle and on Days 19 - 21 of the 3rd and 13th conventional cycle , or on Days 82 - 84 of the first and fourth extended cycle . RESULTS At both time points , the serum concentrations of thyroxine-binding globulin were elevated by about 65 % in both treatment regimens . Likewise , both groups showed an increase in total triiodothyronine ( T3 ) and total thyroxine ( T4 ) by 30 - 40 % , and no change in free T4 . Until the 12th month of conventional treatment , the level of free T3 remained unchanged but decreased slightly during the extended-cycle regimen . In both groups there was a rise of sex hormone-binding globulin by 210 - 230 % after 3 months and by 220 - 250 % after 12 months . The levels of total testosterone were reduced by about 40 % and those of free testosterone by 55 - 65 % after 3 and 12 months . CONCLUSION The results suggest that , during conventional and extended-cycle treatment with EE/DNG , a steady state in the effects on thyroid hormones and and rogen parameters was reached within 3 months and that the changes in the various hormonal parameters did not substantially differ between conventional and extended-cycle regimen
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 .