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 and 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 values of circulating thyroid hormones. Nevertheless, endogenously depressed 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 group 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 function test results in the minor depressed group did not significantly differ from those in the controls. Five of the 9 endogenously depressed patients were subclinically hypothyroid, while none of the 66 patients with minor depressive disorder showed thyroid dysfunction. Antibodies against thyroglobulin and/or thyroid peroxidase were positive in all the 5 endogenously depressed women with subclinical hypothyroidism, revealing a symptomless autoimmune thyroiditis, which was also confirmed by ultrasonography in all cases and histopathologically demonstrated in one case. None of the endogenously depressed women without thyroid dysfunction and none of the 66 minor depressives were seropositive for thyroid autoantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)