Abstract
Study question
Is there a relationship between thyroid autoimmunity and serum level of anti-müllerian hormon (AMH) in infertile women with normal ovarian reserve undergoing in vitro fertilisation (IVF)?
Summary answer
In infertile women with normal ovarian reserve serum AMH level above 5ng/ml is associated with higher level of thyroid hormones and less frequent thyroid autoimmunity
What is known already
Previous studies suggest that thyroid autoimmunity is associated with a decreased ovarian reserve. Moreover, it was reported that thyroid hormone administration could improve serum AMH level. However, the relationship between serum AMH level and thyroid autoimmunity and function in infertile women with normal ovarian reserve undergoing IVF is largely unknown. Since in IVF the serum AMH level is an important marker which dictate the management of the couple, the identification of all the factors possibly related to this parameter is very important. Study design, size, duration: We performed a retrospective study in the Department of Reproductive Medicine of a private hospital. The medical records of all consecutive patients who underwent IVF between January 2015 and December 2018 with all causes of infertility were reviewed. Study group included 581patients with a mean age of 34.4±4.1 years, mean AMH of 3.78±2.4 ng/mL, mean serum TSH level of 1.89±1 microUI/ml and mean serum free T4 level of 1.05±0.98 ng/dl.
Participants/materials, setting, methods
Patients with known thyroid disorders or under thyroid hormone treatment at the moment of evaluation were excluded. Only patients with serum level of thyroid stimulating hormone (TSH), free tyroxine (free T4), anti thyroid peroxidase antibodies (ATPO,) anti thyroglobulin antibodies (ATG), AMH and age available for analysis were included in the study. This parameters are evaluated on a systematic basis in all the patients undergoing IVF in our Department, except very few cases.
Main results and the role of chance
Patients were divided according to their serum AMH level in two groups: group 1 with AMH level 5 ng/ml and below (n = 450 patients) and group 2 with AMH above 5 ng/ml (n = 131 patients). When the two groups were compared we found that patients in group 2 were younger in comparison with patients in group 1 (32.9±3.8 versus 35±4 years, p < 0.0001). After adjustment for age, patients in group 2 had significantly higher serum free T4 level (1.07±0.12 versus 1.04±0.14 ng/dl, p = 0.015), lower ATG (17.59±41.8 UI/ml versus 39.4±136.16 UI/ml, p < 0.018) and presented less frequently with high ATPO antibodies (35% versus 41.8%, p = 0.047). In a logistic regression model with AMH as a dependent variable, free T4, but not TSH was independently and positively associated with higher AMH levels (above 5 ng/ml) (p = 0.025) after adjustment for anti thyroid antibodies levels. Morever, in this logistic model the presence of high ATPO, but not ATG, were negatively related to higher AMH level (p = 0.037).
Limitations, reasons for caution
Patients included in this study are infertile patients with indication for IVF treatment. Therefore, the results of this study should be used with caution in other populations
Wider implications of the findings: Our study suggest that serum AMH level might be related to thyroid autoimmunity, but also to thyroid hormones levels. If confirmed by further studies, this findings could offer a way to improve serum AMH level and to better understand the markers of ovarian reserve in an IVF setting.
Trial registration number
NA
Maternal thyroid function in multifetal pregnancies before and after fetal reduction
