Thyroid hormone levels and recurrence of major depression

Objective: The relationship between basal thyroid hormone levels and acute antidepressant response has been studied, but any relationship between basa l thyroid hormone levels and long-term course of depressive illness has not been evaluated. Method: The authors used a Cox regression survival analysis to evaluate the relationship between life course of depressive illness and basal levels of thyroid hormones (triiodothyronine [T-3], thyroxine [T-4,], and thyrotropi n) in 75 outpatients with unipolar major depressive disorder. Results: Time to recurrence of major depression was inversely related to T- 3 levels but not to T-4 levels. Conclusions: These data may be of clinical interest in view of the fact tha t T-3 is used to augment antidepressant response.