High prevalence of thyroid abnormalities in a Chilean psychiatric outpatient population

The aim of the present study was to establish the prevalence of thyroid disturbances in patients consulting for panic and mood disorders. These data may be relevant because thyroid functional alterations affect the success of treatment in these pathologies. We studied prospectively 268 psychiatric outpatients (204 females and 64 males) diagnosed by DSM-IV criteria. We excluded patients with addictive disorders and major medical disease. We measured TSH, Free T4 (FT4) and antimicrosomal antibodies (AMA). We diagnosed classical hypothyroidism when the TSH value was >10 microUI/ml (NV=0.25-4.3) and subclinical hypothyroidism when the TSH value was between 5-10 microUI/ml. Hyperthyroidism was diagnosed when FT4 >1.4 (NV=0.8-1.4), the TSH suppressed and the radioiodine uptake >20% (NV=5-15). Positive antimicrosomal antibodies (AMA) titres were >1:100 dilution. Hypothyroidism was diagnosed in 26/268 patients (9.7%); 10 cases corresponded to the classical form (38.5%) and 16 cases to the subclinical form (61.5%). Hyperthyroidism was found in 6/268 patients (2.2%). Normal thyroid function with positive AMA was found in 28/268 patients (10.4%). Hypothyroidism was more common in patients with mood disorders, and hyperthyroidism in patients with panic disorders. Patients with panic disorder had significant higher levels of FT4. The prevalence of positive AMA, hypothyroidism and hyperthyroidism was higher in women than men. We found a high frequency of thyroid abnormalities in a psychiatric outpatient population. These data suggests that routine evaluation of thyroid function should be considered in patients consulting for mood and panic disorders.