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Levothyroxine improves ovarian function in infertility, Hashimoto’s thyroiditis
Women with infertility and Hashimoto’s thyroiditis who received levothyroxine supplementation for 3 months experienced an increase in anti-Müllerian hormone levels, a finding not observed in women with subclinical or overt hypothyroidism and infertility, according to findings reported in The Journal of Obstetrics and Gynaecology Research.
“In in vivo research, hypothyroidism has an adverse effect on folliculogenesis, granulosa cell differentiation and steroidogenesis,” Masako Kuroda, MD, of the Shinbashi Yume Clinic in Tokyo, and colleagues wrote. “Levothyroxine (LT4) replacement for hypothyroidism in infertile patients improves implantation and miscarriage rates, leading to successful pregnancy; however, the effect of treatment on ovarian function is poorly understood.”
Kuroda and colleagues analyzed data from 174 women with infertility and elevated thyroid-stimulating hormone measurements ( 2.5 µIU/mL) who were diagnosed with subclinical or overt hypothyroidism and/or Hashimoto’s thyroiditis (elevated TSH and thyroid peroxidase antibodies [TPOAb] or thyroglobulin antibodies [TgAb]) by test results and clinical exams before the start of in vitro fertilization treatment from 2014 to 2015. Researchers evaluated alterations in anti-Müllerian and thyroid-related hormone levels at 1 and 3 months after levothyroxine supplementation during infertility treatment. Researchers defined change ratio as the fold-change in anti-Müllerian hormone level compared with the level before levothyroxine supplementation.
At 3 months, 73 patients in the cohort conceived pregnancy, and anti-Müllerian hormone levels were analyzed in the 101 remaining patients with infertility.
Researchers found that levothyroxine supplementation decreased TSH levels and increased free thyroxine levels in women, but they observed no changes in anti-Müllerian hormone levels in patients with subclinical hypothyroidism at 3 months vs. baseline and 1 month. However, when researchers extracted 35 patients with Hashimoto’s thyroiditis (20.1% of patients with subclinical hypothyroidism), 59.4% and 91.4% had positive rates of TPOAb or TgAb, respectively. In this subgroup of patients with Hashimoto’s thyroiditis, the change ratio of anti-Müllerian hormone was increased by 1.3-fold at 1 month and 3 months after levothyroxine supplementation (P = .001 and .04, respectively), leading researchers to conclude that levothyroxine replacement may relieve the adverse impact on ovaries caused by thyroid autoimmunity and hypothyroidism.
Researchers also stratified the Hashimoto’s thyroiditis subgroup into three groups — TPOAb-positive, TgAb-positive and both TPOAb- and TgAb-positive — and observed a 1.5-fold increase in anti-Müllerian hormone levels at 1 and 3 months among women who were TgAb-positive and TPOAb-negative (P = .023).
“Tg antibody may be a key factor for the recovery of impaired ovarian function with LT4 treatment in infertile women with Hashimoto’s thyroiditis,” the researchers wrote. “Strictly controlled thyroid function is important preconception care to improve ovarian function in order to lead to successful pregnancy.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.