Lack of association between thyroid and pineal responses to antidepressant treatment

With antidepressant treatment for major depression there are decreases in thyroid hormone levels and increases in pineal function. We have conducted a study to examine whether there is a relationship between pineal and thyroid hormone measures as well as between hormone measures and response to treatment in patients treated with desipramine. Measures of thyroid activity included thyroxine, triiodothyronine, T3 resin uptake, and TSH. Pineal function was determined by measurement of 6-suphatoxymelatonin in three consecutive 8 hour pools. Hormone measures as well as Hamilton depression scores were obtained prior to treatment and at the end of 5 weeks of treatment. As in previous studies, thyroid measures decreased, pineal activity increased, and Hamilton scores decreased significantly with treatment. No correlations were found between these measures, suggesting that if there is a relationship between them it is not a direct one.