Subclinical hypothyroidism and thyroid autoimmunity in women with infertility

Objective. To determine the prevalence of different subclinical hypothyroidism (SH) grades and thyroid autoimmunity (TAI) in infertile women. Design. Retrospective study. Setting. Endocrinology division of a public hospital in Argentina. Patients. Group I comprised 244 women consulting on infertility (> 1 year without pregnancy); Group C (controls) comprised 155 healthy women with confirmed fertility. Intervention. Thyroid-stimulating hormone and thyroid peroxidase antibodies were measured in all patients, and a thyrotropin-releasing hormone (TRH) stimulation test was performed in 71 patients to diagnose SH grade 1. The pregnancy rate in hypothyroid women on levothyroxine treatment was also evaluated. Results. SH was diagnosed in 13.9% of the patients in Group I and in 3.9% of Group C (p < 0.002). The TRH stimulation test was useful to detect SH grade 1 in 12.7% of the infertile patients. Patients with precocious ovarian failure, tubal disturbances and ovulatory dysfunction presented higher SH rates (40.0, 18.2 and 15.4%, respectively) than control patients (p < 0.0001, p < 0.002 and p < 0.003). No significant difference in TAI prevalence was shown in Group I relative to Group C. Pregnancy rate of 44.1% was achieved under levothyroxine treatment. Conclusions. We observed a higher prevalence of SH, but not of TAI, in patients with infertility. Our results support thyroid screening in women with reproductive failure.