PRL and endometriosis: However, a meta-analysis on 122 blood markers for the non-invasive diagnosis of endometriosis including the prolactin serum levels stated that despite the high specificity, the sensitivity for the prolactin serum levels was low and the thresholds remained unacceptably low, even for a triage test, and the data regarding prolactin and other hormonal biomarkers such as oestradiol, progesterone, LH, and FSH for the diagnosing of endometriosis were not sufficient to draw meaningful conclusions [61].