Relationship between anti-Müllerian hormone and antral follicle count across the menstrual cycle using the Beckman Coulter Access assay in comparison with Gen II manual assay

BACKGROUND: The study aim was to validate Beckman Coulter's fully automated Access Immunoassay System (BC Access assay) for anti-Müllerian hormone (AMH) and compare it with Beckman Coulter's Modified Manual Generation II assay (BC Mod Gen II), with regard to cycle AMH fluctuations and antral follicle counts. METHODS: During one complete menstrual cycle, transvaginal ultrasound was performed on regularly menstruating women (n=39; 18-40years) every 2 days until the dominant ovarian follicle reached 16mm, then daily until observed ovulation; blood samples were collected throughout the cycle. Number and size of antral follicles was determined and AMH levels measured using both assays. RESULTS: AMH levels measured by the BC Access assay vary over ovulatory menstrual cycles, with a statistically significant pre-ovulatory decrease from -5 to +2 days around objective ovulation. Mean luteal AMH levels were significantly lower (-7.99%) than mean follicular levels but increased again towards the end of the luteal phase. Antral follicle count can be estimated from AMH (ng/mL, BC Access assay) concentrations on any follicular phase day. BC Access assay-obtained AMH values are considerably lower compared with the BC Mod Gen II assay (-19% on average); conversion equation: AMH BC Access (ng/mL)=0.85 [AMH BC Mod Gen II (ng/mL)]0.95. CONCLUSIONS: AMH levels vary throughout the cycle, independently of assay utilised. A formula can be used to convert BC Access assay-obtained AMH levels to BC Mod Gen II values. The number of antral follicles can be consistently estimated from pre-ovulatory AMH levels using either assay.