The usefulness of a thyrotropin-releasing hormone stimulation test in subfertile female patients

Background. The thyrotropin-releasing hormone (TRH) stimulation test is widely used as a screening procedure in subfertile patients to identify subclinical hypothyroidism. However, its usefulness in daily clinical practice has not been proven, despite more than 30 years of use.

Material and methods. We analyzed data from a cohort of 371 consecutive female subfertility patients, who were screened with an intravenous TRH test when they came for the first evaluation. All patients with positive thyroid peroxidase antibodies, basal TSH <1.5 mU/l, known thyroid disease or actual thyroid medication were not screened and excluded from the analysis.

Results. We found a good correlation between basal and stimulated levels of thyroid-stimulating hormone (TSH). Basal TSH and the difference between stimulated and basal TSH did not correlate with prolactin levels. Definition of a positive TRH test (difference of 15 or 20 mU/l) did not have sufficient sensitivity and specificity, as confirmed by analysis of receiver operating characteristic curves, to identify subclinical hypothyroidism.

Conclusion. TRH stimulation testing is not helpful to identify patients with subclinical hypothyroidism and should not be part of initial screening in this group.