SR Lincoln, et al (Univ of Tenessee, Memphis)
Screening for Hypothyroidism in Infertile women
J Reprod Med 44: 455-457, 1999.
Background – Previous research has suggested that infertility is closely associated with hypothyroidism. However, the incidence of hypothyroidism in infertile women is estimated to be less than 1%, and many clinicians question the value of including routine screening for hypothyroidism as part of the infertility assessment. The frequency of increased thyroid stimulating hormone (TSH) in patients with a history of infertility seen at reproductive endocrinology and infertility centers was investigated.
Conclusions – The prevalence of increased TSH was 2.3% in this group of women with infertility of at least 1 year’s duration. Most women with a diagnosis of hypothyroidism had ovulatory dysfunction. When their hypothyroidism was treated, 64% were able to become pregnant. Thus infertile women with ovulatory dysfunction should be screened for hypothyroidism.
Many clinicians measure TSH and prolactin levels in all women with a history of infertility who wish to conceive in this study, fewer than 1% of infertile women with normal ovulatory cycles had an elevated TSH level. None of these women conceived after being treated with levothyroxine. However, 7 of 11 women with evidence of ovulatory dysfunction and elevated TSH levels conceived after being treated with levothyroxine. Thus, it appears cost-effective to measure TSH levels in infertile women without regular ovulatory cycles so as to detect and treat subclinical hypothyroidism.
The benefit of measuring TSH, as well as prolactin, in infertile women with regular ovulatory cycles remain to be established. If either of these assays is abnormal in women with regular ovulatory menstrual cycles, treatment with bromocriptine or levothyroixne has not been shown to improve fecundity.