Free T4 index and clinical outcome in patients with depression

IntroductionMany studies of patients with major depression have reported that a significant decrease in serum free T4 index is associated with specific treatments; what has been unanswered is whether these observations are generalizable. This study evaluated baseline thyroid function and its relationship to rapidity of treatment response as measured by hospital length of stay (HLOS).MethodsAdmission thyroid indices and HLOS data were harvested from the medical record of patients hospitalized for depression, both unipolar and bipolar. The relationship between admission thyroid indices and HLOS was evaluated using survival models.ResultsControlling for age and year of discharge, an inverse relationship between FT4 index (FT4I) and HLOS was present in men, but not in women. The mean HLOS stratified by gender and median FT4I was 50% shorter in men with a relatively high FT4I in comparison to the other three groups.LimitationsThis is a retrospective study limited by the absence of a structured diagnostic psychiatric interview and prospective controlled antidepressant evaluation.ConclusionThese data would suggest that a relatively elevated FT4 index in depressed men is associated with a faster antidepressant response time. Prospective study is encouraged to further clarify this potential thyroid/gender relationship and whether thyroid supplementation can accelerate the improvement in depression as measured by HLOS.