Screening for hypothyroidism in infertile women

To determine the frequency of an elevated thyroid-stimulating hormone (TSH) level in 704 patients seeking treatment for infertility.

Sera from 704 women evaluated for infertility were assayed for TSH levels using radioimmunoassay (normal, 0.45-4.09 mIU/mL). All women had at least one year of infertility. Women with a known history of thyroid disease were excluded from the review.

Sixteen of 704 patients (2.3%) had elevated TSH levels and were treated with levothyroxine to normalize TSH. None of these women had overt clinical signs or symptoms of hypothyroidism. Of these women, 11 of 16, or 69%, had ovulatory dysfunction, and 7 (64%) later became pregnant while on thyroid replacement. Five of 704 (0.7%) women with infertility who presented without a history of ovulatory dysfunction had elevated TSH levels, and none became pregnant with treatment.

The prevalence of elevated TSH in 704 women with at least one year of infertility was 2.3%. The majority of women diagnosed with hypothyroidism (11 of 16, or 69%) had ovulatory dysfunction. With treatment for hypothyroidism, successful pregnancies resulted in 7 of 11 (64%) of patients. Women with infertility and ovulatory dysfunction should be screened for hypothyroidism. Screening for hypothyroidism as part of a routine infertility workup in women with normal ovulatory function will yield few abnormal tests.