Assessment of the effects of levothyroxine treatment on cardiac functions in children with subclinical hypothyroidism

Object: The aim of this study is to assess cardiac functions in children with subclinical hypothyroidism and investigate the effect of levothyroxine treatment on these functions. Cases and Method: In the study group, which consists of 16 prepubertal cases at an average chronological age (CA) of 7,41 years, thyroid function tests (fT3, fT4, TSH) and echocardiographic parameters (cardiac systolic functions, cardiac diastolic functions and cardiac tissue Doppler indicators) were evaluated at the beginning and compared with the data obtained on the third and sixth months of treatment. Findings: TSH levels were found to be significantly decreased at the end of 3- and 6-month treatment period in 16 and 9 cases, respectively, whereas there was no significant difference in fT3 and fT4 levels. There was a significant increase in ME/A ratio on the third month of treatment compared to the pretreatment value. Neither systolic functions and cardiac tissue Doppler indicators in the whole duration of treatment nor diastolic functions in 9 cases on the sixth month of the treatment showed significant difference compared to pretreatment values. Discussion: The results of the study is found to be supportive for the hypothesis tested. It is suggested that L-T4 treatment applied in physiological dose to maintain euthyroid status is reliable in childhood while it prevents the possible negative consequences of subclinical hypothyroidism and creates no negative effects on cardiac functions. The improvement in diastolic functions observed in a short term would be evaluated more accurate with more cases and much longer follow-up