Depressive symptoms very often could be the only manifestation of the subclinical thyroid dysfunction (STD). Patients with the STD have the lifetime prevalence of depression approximately double that in the general population and display a lower response rate to antidepressant treatment and greater likelihood of responding to liothyronine augmentation.

To assess the stimulate-thyroid hormone (TSH) levels in the first depressive episode (FDE) sample and to evaluate the correlation between severity of depressive symptoms and the TSH levels.

The study included 27 patients with FDE (ICD X, F 32) treated in Psychiatric Hospital, University Hospital Zvezdara (Belgrade, Serbia). The exclusion criteria were presence of detected thyroid dysfunction, other psychiatric disorder, chronic somatic disease and/or using drugs. The TSH blood levels were measured. The 21-item Hamilton Rating Scale for Depression (HDRS, scored >17) was used in order to evaluate the severity of depression.

Mean age in our sample was 48.6 years, with female predominance (55.6 %). We found TSH levels elevated (>5.5 mEg/L) in 11.1 % (all were females) and decreased (<0.4 mEg/L) in 11.1 % (p<.05). We found positive correlation between the HDRS scores and the TSH measures (r=.445, p<.05).

The STD is a risk factor for developing the FDE. The greater TSH levels imply the greater severity of the FDE. Each clinician should be aware of possible underlying the STD with its implications on diagnosis, treatment and prognosis of the FDE.