SUBCLINICAL HYPOTHYROIDISM RESULTING FROM AUTOIMMUNE-THYROIDITIS IN FEMALE-PATIENTS WITH ENDOGENOUS-DEPRESSION

Thyroid function and presence of thyroid autoantibodies were assessed in a group of 75 consecutive female patients with mood disturbances an d in a group of 38 healthy women of similar age recruited as controls. Nine patients suffered from major (endogenous) depression and 66 from minor (neurotic) depression. The individual patients had normal value s of circulating thyroid hormones. Nevertheless, endogenously depresse d patients had total serum triiodothyronine (M+/-SE=1.49+/-0.09 nmol/l ) and both total (83.9+/-4.3 nmol/l) and free serum thyroxine (13.9+/- 1.1 pmol/l) lower than in the group of minor depressed and in the grou p of controls (p<0.01, in both comparison). The median value of serum thyrotropin was 5.22 mU/l in the major depressed patients versus 1.72 mU/l in the minor depressed and 1.69 mU/l in the controls. Thyroid fun ction test results in the minor depressed group did not significantly differ from those in the controls. Five of the 9 endogenously depresse d patients were subclinically hypothyroid, while none of the 66 patien ts with minor depressive disorder showed thyroid dysfunction. Antibodi es against thyroglobulin and/or thyroid peroxidase were positive in al l the 5 endogenously depressed women with subclinical hypothyroidism, revealing a symptomless autoimmune thyroiditis, which was also confirm ed by ultrasonography in all cases and histopathologically demonstrate d in one case. None of the endogenously depressed women without thyroi d dysfunction and none of the 66 minor depressives were seropositive f or thyroid autoantibodies. Only one of the non-depressed women in the control group was found seropositive for TPO-Ab and showed an exaggera ted TSH responsiveness to TRH stimulation. The findings indicate the p ossibility that endogenous depression is accompained by latent hypothy roidism in an appreciable proportion of women. The detection of thyroi d autoantibodies in such patients suggests that affective disorders mi ght play a precipitating role in the development of thyroid autoimmune disease. Therefore the possibility of immunological damage should be taken into consideration whenever depressed women display biochemical thyroid dysfunction.