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 .
Total testosterone assays in women with polycystic ovary syndrome: precision and correlation with hirsutism.
CONTEXT There is no st and ardized assay of testosterone in women .  Liquid chromatography mass spectrometry ( LC/MS ) has been proposed as the preferable assay by an Endocrine Society Position Statement . OBJECTIVE The aim was to compare assay results from a direct RIA with two LC/MS . DESIGN AND SETTING We conducted a blinded laboratory study including masked duplicate sample s at three laboratories -- two academic ( University of Virginia , RIA ; and Mayo Clinic , LC/MS ) and one commercial ( Quest , LC/MS ) . PARTICIPANTS AND INTERVENTIONS Baseline testosterone levels from 596 women with PCOS who participated in a large , multicenter , r and omized controlled infertility trial performed at academic health centers in the United States were run by varying assays , and results were compared . MAIN OUTCOME MEASURE We measured assay precision and correlation and baseline Ferriman-Gallwey hirsutism scores . RESULTS Median testosterone levels were highest with RIA . The correlations between the blinded sample s that were run in duplicate were comparable . The correlation coefficient ( CC ) between LC/MS at Quest and Mayo was 0.83 [ 95 % confidence interval ( CI ) , 0.80 - 0.85 ] , between RIA and LC/MS at Mayo was 0.79 ( 95 % CI , 0.76 - 0.82 ) , and between RIA and LC/MS at Quest was 0.67 ( 95 % CI , 0.63 - 0.72 ) . Interassay variation was highest at the lower levels of total testosterone ( ≤50 ng/dl ) . The CC for Quest LC/MS was significantly different from those derived from the other assays . We found similar correlations between total testosterone levels and hirsutism score with the RIA ( CC=0.24 ) , LC/MS at Mayo ( CC=0.15 ) , or Quest ( CC=0.17 ) . CONCLUSIONS A testosterone RIA is comparable to LC/MS assays . There is significant variability between LC/MS assays and poor precision with all assays at low testosterone levels
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 .