Context: Primary Ovarian Insufficiency (POI) is defined by hypergonadotropic amenorrhea occurring before the age of 40 yrs. In 4–5% of women with POI, an ovarian autoimmune process can be demonstrated.

Design: We have determined the serum concentrations of total inhibin and inhibin B by sensitive ELISAs in 22 women with autoimmune POI (aPOI), 71 women with non-autoimmune, idiopathic POI (iPOI), 77 post-menopausal women (PMW) and 90 healthy, fertile women (HW). Diagnosis of aPOI was made according to the presence of steroid cell autoantibodies and/or 17-hydroxylase autoantibodies and/or P450scc autoantibodies. All aPOI patients were also positive for adrenal autoantibodies.

Results: Total inhibin levels were significantly higher in women with aPOI (median: 281 pg/ml) than in women with iPOI (median: 74 pg/ml) or HW (median: 133.5 pg/ml) (p<0.001). Levels of inhibin B were also significantly higher in women with aPOI (median: 109 pg/ml) than in women with iPOI (median: 18 pg/ml) (p<0.001) or HW (median: 39 pg/ml) (p<0.05). Serum concentrations of total inhibin and inhibin B were significantly higher in women with POI than in PMW (p<0.001), irrespective of the presence/absence of autoantibodies. At ROC analysis, cut off-values of 133 pg/ml for total inhibin and 60.5 pg/ml for inhibin B ensured a 86.4% sensitivity and a 81–84.5% specificity for aPOI vs. iPOI.

Conclusions: We conclude that a variable degree of ovarian function is preserved in women with primary ovarian insufficiency and that aPOI is characterized by increased inhibin production resulting from a selective theca cell destruction, with initial preservation of granulosa cells.