Basal Thyroid Indices in Adolescent Depression and Bipolar Disorder

Abstract

Abnormalities of the thyroid axis are documented in adult mood disorders. The most consistent findings have been observed in major depressive disorder with elevations of thyroxine (T4) or free-T4 (fT4) within the euthyroid range that decrease with treatment. The literature on adolescents is limited, and it is unknown whether similar findings might be present in this population. First admissions to a university hospital adolescent psychiatry unit were reviewed. Fourteen depressed and 13 manic patients satisfied inclusion and exclusion criteria. None had a history of thyroid illness or medical illness or were taking medications known to affect thyroid function. Basal serum thyrotropin, T4, fT4, triiodothyronine (T3), reverse-T3, free thyroxine index (FTI), and T3 resin uptake levels were compared with those of a group of adolescent normal controls. T4 (but not fT4) was elevated in depressed and manic patients compared with controls (p < .05). In manic patients, T3 was decreased and reverse-T3 was increased (p < .05). There were no significant differences in relation to age, sex, or suicidality. We observed significant differences in basal thyroid hormone levels in depressed and manic adolescents. Our results suggest the presence of abnormalities of thyroid function in adolescent mood disorders similar to those described in mood-disordered adults.