Serum Osteopontin Levels Are Decreased in Focal Adenomyosis

We investigated whether serum osteopontin (OPN) levels are different according to specific phenotypes of adenomyosis and endometriosis. We conducted a prospective laboratory study in a university referral center for endometriosis between May 2005 and May 2013 and included 148 nonpregnant women, younger than 42 years, undergoing surgery for a benign gynecological condition and who had a preoperative pelvic magnetic resonance imaging (MRI). The presence of focal and/or diffuse adenomyosis was determined by pelvic MRI, and women were classified into 3 groups: no-adenomyosis (No-AM), isolated diffuse adenomyosis (DIF-AM), and focal adenomyosis with or without diffuse adenomyosis (FOC-AM). After complete surgical exploration of the pelvic cavity, the presence and type of endometriosis was surgically determined and histologically confirmed. We distinguished 4 phenotypes: no endometriosis, superficial peritoneal endometriosis (SUP), ovarian endometrioma, and deep infiltrating endometriosis (DIE). Osteopontin levels were measured by enzyme-linked immunosorbent assay in serum samples obtained in all participants in the month preceding surgery. Our results show lower OPN levels in women with focal adenomyosis compared to adenomyosis-free controls. Our results also show a decrease in OPN levels in women with associated DIE and focal adenomyosis compared to women with SUP. Various serum biomarkers have been studied in the context of endometriosis severity and subtypes, whereas data on serum markers of adenomyosis are scarce. Both entities are often associated, and adenomyosis could be a confounding factor influencing results. Future research on serum biomarkers should describe subtypes of adenomyosis and endometriosis and analyze results according to well-defined subtypes.