TSH response to TRH in depression with and without panic attacks.

Low thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) has been repeatedly described in approximately 25% of patients with major depression. Panic disorder appears related to depression along several dimensions, including prevalence of low TSH response to TRH. The authors divided 46 patients with primary unipolar depression by gender and by presence or absence of concurrent panic attacks and compared their TRH test results with those of 106 normal control subjects, controlling for confounding variables. Depressed patients with panic had higher prevalence of low TSH response and significantly lower mean TSH response than depressed patients without panic. The latter were indistinguishable from normal control subjects.