Thyroid function in clinical subtypes of major depression: an exploratory study

Background: Unipolar depression might be characterized by a 'low-thyroid function syndrome'. To our knowledge, this is the first study which explores the possible relationship of DSM-IV depressive subtypes and the medium term outcome, with thyroid function. Methods: Material: Thirty major depressive patients (DSM-IV) aged 21-60 years and 60 control subjects were included. Clinical Diagnosis: The SCAN v 2.0 and the IPDE were used. The psychometric Assessment included HDRS the HAS and the GAF scales. Free-T3, Free-T4, TSH, Thyroid Binding Inhibitory Immunoglobulins (TBII), Thyroglobulin antibodies (TA) and Thyroid Microsomal Antibodies (TMA) were measured in the serum. The Statistical analysis included 1 and 2-way MANCOVA, discriminant function analysis and Pearson Product Moment Correlation Coefficient. Results: All depressive subtypes had significantly higher TBII levels in comparison to controls. Atypical patients had significantly higher TMA in comparison to controls. No significant correlation was observed between the HDRS, HAS and GAF scales and thyroid indices. Discriminant function analysis produced functions based on thyroid indices, which could moderately discriminate between diagnostic groups, but could predict good response to treatment with 89.47% chance of success. Conclusion: Although overt thyroid dysfunction is not common in depression, there is evidence suggesting the presence of an autoimmune process affecting the thyroid gland in depressive patients