Sex Hormone Binding Globulin Capacity as an Index of Oestrogenicity or Androgenicity in Women on Oral Contraceptive Steroids

SUMMARY Plasma sex hormone binding globulin capacity (SHBC) measurements were evaluated in 125 women with a pre‐treatment mean value of 41 ± 17 nmol/l SHBG and during 3 to 36 cycles of either combination oestrogen and progestagen oral contraceptives (OC) or low progestagen‘mini’pills. An oestrogenic effect or significant elevation of SHBC was noted on combination OC or ethiriyl oestradiol with megestrol acetate, comparable with pregnancy levels (305 t 47 nmol/l SHBC or Volidan), whilst megestrol acetate alone (500 μg) caused a smaller but still significant rise of SHBG. Combination of ethinyl oestradiol with norethisterone acetate (Minovlar Loestrin) produced increased SHBG but ethinyl oestradiol combined with d‐norgestrel (Ovranette) caused no change in mean SHBG. An androgenic effect or significant lowering of mean SHBG to 24 ± 11 nmol/l in women on dl‐norgestrel (75 μg) and a decrease of mean SHBG on norethisterone (350 μg) daily indicated that these 19‐norderivatives are contraindicated in women with low pre‐treatment levels of SHBG or any clinical manifestation or history of androgenic hyperactivity. Combined OC preparations causing some elevation of SHBG might be preferable. Conversely women with a high pre‐treatment SHBG level might be more suited to combination OC with d‐norgestrel or the 19‐norprogestagen‘mini’pills. The characteristic response to SHBC for the group of oral contraceptives used was maintained throughout medication but on discontinuing the SHBC levels returned to pre‐treatment values.