"Symptomless" autoimmune thyroiditis in depression

The magnitude of the thyroid-stimulating hormone (TSH) response induced by thyrotropin-releasing hormone (TRH) helps identify patients whose thyroid is failing. Many of these patients have been found to have Hashimoto's thyroiditis, symptomless autoimmune thyroiditis (SAT), and subclinical hypothyroidism. While patients with SAT are clinically euthyroid, what might be "symptomless" for the endocrinologist might be a syndrome presenting with psychiatric symptoms to the psychiatrist. As a preliminary test of this hypothesis, we tested 100 consecutive admissions to a psychiatric hospital who complained of depression or lack of energy. Fifteen (15%) of 100 patients were identified from the baseline thyroxin (T4), triiodothyronine (T3) resin uptake (RU), T3 radioimmunoassay (T3RIA), TSH, and TRH test who met criteria for either subclinical, mild, or overt hypothyroidism. Of these 15 patients, 9 (60%) had positive thyroid microsomal antibodies with titers of greater than or equal to 1:10. Our data suggest that SAT is not symptomless and may be an important diagnosis to consider in the evaluation of depressed, anergic, or atypical patients.