Endocrine Abstracts

PCOS is a common pathology in women of reproductive age, and ~70% of affected women remain undiagnosed. Clinical features of PCOS include ovulatory dysfunction, hyperandrogenism and PCOM (Rotterdam criteria). Replacement of transvaginal ultrasound (TVUS) with a blood test for PCOM is clinically desirable, as lack of access to TVUS may contribute to underdiagnosis of PCOS. We aimed to derive and validate a cut-off for AMH to discriminate PCOM using the Elecsys AMH Plus immunoassay. APHRODITE is a case-control study of PCOS-positive (cases) and PCOS- negative (controls) women aged 25–45 years. Cases were defined using Rotterdam criteria, showing the full phenotype A (irregular cycles/ovulatory dysfunction, clinical or biochemical hyperandrogenism and PCOM); controls had an antral follicle count (AFC) ≤ 20, based on the new international guideline for PCOS. The discovery cohort included 484 cases and 575 controls; the validation cohort consisted of 455 cases and 500 controls. Serum levels of AMH were measured using the Elecsys AMH Plus immunoassay, and AFC was determined by TVUS. An AMH cut-off was optimised in the discovery cohort based on concordance analysis. Performance (sensitivity, specificity and area under the curve [AUC]) of the defined cut-off was evaluated in the validation cohort. Exploratory analyses in different sub-cohorts (including age groups) were performed. Compared with controls, PCOS cases were younger (median age, 29.0 vs 36.0 years), with a higher median body mass index (discovery, 28.3 vs 23.6 kg/m²; validation, 28.1 vs 23.7 kg/m²) and higher median AMH level (discovery, 6.13 vs 1.59 ng/ml; validation, 6.32 vs 1.58 ng/ml). Good correlation was observed between AMH and AFC in the discovery and validation cohorts, with Spearman correlation coefficients of 0.84 and 0.85, respectively. A serum AMH cut-off of 3.2 ng/ml (23 pmol/l) was determined in the discovery cohort, which achieved 86.2% sensitivity and 86.1% specificity. In the validation cohort, this cut-off achieved 88.6% (95% confidence interval [CI] 85.3–91.3) sensitivity and 84.6% (95% CI 81.1–87.7) specificity, with an AUC of 93.6% (95% CI 92.2–95.1). In women aged ≤ 35 years, the AMH cut-off of 3.2 ng/ml showed 88.5% (95% CI 86.2–90.5) sensitivity and 80.3% (95% CI 76.6–83.6) specificity; in women aged > 35 years, specificity remained high (90.1%; 95% CI 87.3–92.5) but sensitivity was lower (77.8%; 95% CI 66.4–86.7). The Elecsys AMH Plus immunoassay provides a robust method for identifying PCOM as part of PCOS diagnosis with a cut-off of 3.2 ng/mL (23 pmol/l).