These effects are decreased by extraction and chromatography preceding the RIA. Anemarsaponin-BIII However, inaccurately higher testosterone levels in an RIA have been demonstrated previously, even with preceding extraction, as has the disparity between assays when compared across the normal female range. Progesterone levels in the follicular phase range demonstrated the greatest discrepancy between assays, which may be an Eleutheroside-E important consideration if the rise in progesterone becomes an important factor to predict IVF success. Of note, testosterone levels using the RIA were associated with the lowest error, on average 31%, in the current study and similar to previous testosterone errors. Further, there was no difference in the discrepancy between assays in women with PCOS and controls. Taken together, the relatively low percent difference between RIA and LC-MS/MS for testosterone measurements suggests that the RIA could remain an acceptable assay for studies involving women with PCOS. In women with PCOS, 17OH progesterone, androstenedione and testosterone levels are elevated compared to those in control women. These data expand earlier findings comparing hormone levels in the follicular phase using a radioimmunoassay. The higher 17OH progesterone, androstenedione and testosterone levels could represent a contribution from the ovary or the adrenal gland. However, the current data in which DHEA, DHEAS and other predominantly adrenal steroids were not different between women with PCOS and control women support the ovary as the source of hyperandrogenism in PCOS, along with previous data. Further evidence for the ovarian source of androgens in PCOS comes from studies of isolated theca cells from women with PCOS and control women. Progesterone, 17OH progesterone, DHEA, androstenedione and testosterone levels were elevated in theca cells from women with PCOS compared to those from controls. In addition, side chain cleavage, 3b-hydroxysteroid dehydrogenase and 17a-hydroxylase/17,20 desmolase enzymes have increased activity in theca cells of women with PCOS. In the current data, higher 17OH progesterone, androstenedione and testosterone levels, but not progesterone or DHEA are consistent with the in vitro findings in theca cells. While product-toprecursor ratios do not measure enzyme activity, the greater androgen steroid concentration and androgen product-to-precursor ratio for 3b-hydroxysteroid dehydrogenase in women with PCOS compared to controls are also consistent with data from isolated theca cells. In contrast, the product-to-precursor ratio was not increased for adrenal-corticosteroid producing enzymes in women with PCOS. These data require direct testing of enzyme activity for confirmation. One limitation of the current study is that steroids were measured in the absence of exogenous stimulation. However, the PCOS and control subjects did have their blood drawn in the morning, fasting, so that the levels reflect endogenous morning ACTH stimulation. Previous studies demonstrate that urinary steroid metabolites produced by the 5a-reductase pathway 
and the 11b-hydroxysteroid dehydrogenase pathway are increased in women with PCOS compared to controls in the early follicular phase, suggesting increased cortisol production and clearance.