THYROID AUTOANTIBODIES AND THE RESPONSE TO THYROTROPIN-RELEASING-HORMONE IN PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

Aim-To evaluate the clinical usefulness of the thyrotropin releasing h ormone (TRH) test and estimation of thyroid autoantibody concentration s in patients with borderline raised thyroid stimulating hormone (TSH) . Methods-The records of 34 consecutive patients with persistent borde rline increased TSH (4.4-9.9 mU/l) referred to the Medical Investigati on Unit were reviewed. The response of patients with thyroid autoantib odies to the TRH test was compared with that of patients with a negati ve antibody screen. Results-Eleven (44%) of 25 patients with positive anti-thyroid microsomal and/or thyroglobulin antibody tests and three (33%) of nine patients with a negative antibody screen had hypothyroid responses to TRH. Neither age nor sex affected the response to TRH. B asal TSH alone was poorly correlated with these indices. Twelve (35%) patients who had elevated basal TSH had a normal response to the TRH t est. Conclusion-Patients with positive or negative thyroid autoantibod ies and an exaggerated response to the TRH test should be regarded as hypothyroid and treated with thyroxine. Patients with positive thyroid autoantibodies and normal TSH response may subsequently develop hypot hyroidism and should be given long term follow up.