Hypothalamic-pituitary-thyroid system activity during lithium augmentation therapy in patients with unipolar major depression.
OBJECTIVE
Lithium augmentation is an established strategy in the treatment of refractory depression, but little is known about predictors of response and its mode of action. There is increasing evidence that low thyroid function indices within the normal range are associated with a poorer treatment response to antidepressants, but previous studies on the hypothalamic-pituitary-thyroid (HPT) system during lithium augmentation provide inconclusive results and have methodological limitations. This study aimed at exploring the role of thyroid function in lithium augmentation and used a prospective design that included a homogeneous sample of inpatients with unipolar major depressive disorder.


METHODS
In 24 euthyroid patients with a major depressive episode who had not responded to antidepressant monotherapy of at least 4 weeks, we measured serum thyroid-stimulating hormone (TSH), total triiodothyronine (T3) and total thyroxine (T4) before (baseline) and during lithium augmentation therapy (follow-up). The time point of the endocrinological follow-up depended on the status of response, which was assessed weekly with the Hamilton Depression Rating Scale, 17-item version (HDRS17). Responders were reassessed immediately after response was determined, and non-responders after 4 weeks of lithium augmentation.


RESULTS
There was a statistically significant change in thyroid system activity during lithium augmentation, with an increase of TSH levels and a decrease of peripheral T3 and T4 levels. However, there were no differences in any of the HPT hormones between responders and non-responders at baseline or at follow-up.


CONCLUSIONS
The decrease of thyroid system activity during lithium treatment reflects the well-established "antithyroid" properties of lithium. However, it appears that thyroid status does not predict response to lithium augmentation in euthyroid patients before treatment.
Bschor
Tom
T
Department of Psychiatry, Technische Universität Dresden, Dresden, Germany. bschor@mailbox.tu-dresden.de
Baethge
Christopher
C
Adli
Mazda
M
Lewitzka
Ute
U
Eichmann
Uta
U
Bauer
Michael
M
D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use*; D003865:Major Depressive Disorder / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects*; D016651:Lithium Carbonate / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use*; D008297:Male; D010913:Pituitary-Adrenal System / Q000187:drug effects*; D013961:Thyroid Gland / Q000187:drug effects*
D014150:Antipsychotic Agents; D016651:Lithium Carbonate