Anti-Mullerian hormone as a predictor of ovarian reserve in ART protocols: the hidden role of thyroid autoimmunity

BACKGROUND: Protocols of controlled ovarian hyper-stimulation (COH) require, as a crucial step, the identification of reliable predictors of ovarian reserve. Anti-Mullerian hormone (AMH) is one of the most reliable predictors of ovarian reserve but other factors including autoimmune thyroid diseases (ATD) have been associated with reduced fertility and poor COH outcome. Aim of the present study was to evaluate the relationship between ATD and AMH, and their role on the outcome of COH. METHODS: The study group included 288 sub-fertile euthyroid women aged less than 40 years attending a single center for Reproductive Medicine. Among them, 55 were ATD-positive and 233 ATD-negative. The serum levels of AMH, FSH, LH, estradiol (E2), and TSH were measured before COH. The ratio between serum E2 concentration on the day of oocytes pick-up and the total dose of administered recombinant FSH (r-FSH) (E2/r-FSH ratio) was calculated. RESULTS: The serum levels of AMH were significantly related to E2/r-FSH ratio, total dose of r-FSH and number of M II oocytes, both in ATD-positive and ATD-negative women. Within the low stratum of AMH levels, the presence of ATD did not further affect the outcome of COH. When the serum levels of AMH were in the high stratum, the presence of ATD significantly affected the E2/rFSH ratio, the total dose of r-FSH and the number of M II oocytes. CONCLUSIONS: The probability of a poor response to COH is high, and independent from ATD, in women with low AMH serum levels. In women with a good ovarian reserve, as assessed by high AMH serum levels, the presence of ATD impairs the outcome of COH.