Evaluation of anti-Müllerian hormone in pre-menopausal women stratified according to thyroid function, autoimmunity and age

Abstract

Background AMH is a reliable index of ovarian reserve. It is not clear whether, or how much, thyroid function and/or thyroid autoimmunity can impair ovarian function and AMH secretion in the long term. Aim This retrospective cross-sectional study compared AMH levels in pre-menopausal women with/without positive thyroid autoimmunity or hypofunction. Methods From January 2019 to May 2022, AMH was evaluated in 250 pre-menopausal women not undergoing assisted fertility procedures who were referred to a secondary endocrine centre. Thyroid function and autoimmunity, sonographically measured thyroid volume, FSH and E2 in the early follicular phase, and PRL and progesterone in the luteal phase were also evaluated. Exclusion criteria were: age < 18 years, genetic hypogonadism, pregnancy and previous treatments that have potentially damaging effects on gonads. Results We evaluated 171 women (mean age ± SD: 31.5 ± 9.0 years) off L-T4 treatment and 79 women on L-T4 treatment (39.7 ± 9.5 years; P < 0.001). AMH (median, IQR, CI) was 16.1 pmol/l (7.1 – 35.7 pmol/l, 21.4 – 29.9 pmol/l) and 7.6 pmol/l (1.4 – 17.8 pmol/l, 8.6 – 14.7 pmol/l; P < 0.001), respectively. When the women were stratified according to age (18-25, 26-30, 31-35, 36-40, 41-45, > 46 years) no significant difference emerged between those on/off L-T4 treatment in groups of the same age-range. In women on- or off-L-T4 treatment, AMH was negatively related with age on univariate and multivariate analyses (P < 0.0001). In both groups, AMH was negatively related to FSH (P < 0.0001). On multivariate analysis, AMH was positively related to the age of the mother on spontaneous menopause (P = 0.006) and negatively to thyroid volume (P = 0.02) in women on L-T4. AMH levels were significantly (P = 0.03) higher in TPOAb-negative than in TPOAb-positive women, but age was significantly (P = 0.001) lower in TPOAb-negative than in TPOAb-positive women. Conclusions In our cohort of women, age proved to be a better predictor of AMH levels than any of the other factors linked to thyroid function and autoimmunity. Our data do not support the hypothesis that subclinical hypothyroidism and/or autoimmunity are associated with decreased ovarian reserve. However, a larger number of cases is needed in order to obtain conclusive data.

Polycystic ovary syndrome and thyroid disorder: a comprehensive narrative review of the literature

“…A more recent study ( 105 ) in infertile women, including patients with subclinical and clinical hypothyroidism, confirmed a relationship between TSH levels and the ovarian reserve in women aged >35 years only. Although these data are not in agreement with other studies ( 93 , 101 – 104 , 106 ), one unit increase in TSH level was associated with a 25% increased risk of an AMH level <1.1 ng/ml and an increase in serum TSH values greater than the cutoff of 1.465 mIU/L was associated with a decrease in ovarian function in these patients ( 105 ). More recently ( 106 ) a Chinese study demonstrated that the ovarian reserve may be affected only in women with TSH levels >2.5 mIU/L and an anti-TPO Ab >100 IU/ml.…”

“…No effect of anti-TG Ab was detected on ovarian function (menstrual pattern) or biochemical/clinical hyperandrogenism ( 92 ). More recently, serum AMH levels were significantly higher in anti-TPO Ab-negative versus anti-TPO Ab-positive women, but it is important to note that patient age was significantly lower in anti-TPO Ab- negative versus anti-TPO- Ab-positive women, highlighting the influence of age on AMH levels ( 93 ). Conversely, other studies ( 58 , 94 , 95 ) reported high autoantibody levels against ovarian tissue in women with PCOS.…”