Abstract
The levels of TSH, T3 and T4 were estimated in 40 cases in which lithium was used for treatment. 5 mlU/L was considered as a limit for TSH concentration – above this limit subclinical hypothyroidism was diagnosed. The subclinical hypothyroidism was found in 4 cases (10% of patients). The neuropsychological test after substitutional treatment by L-thyroxine showed the improvement of memory functions of those patients.