Effects of Levothyroxine Treatment on Cardiac Functions in Infants with Compensated Hypothyroidism

Introduction: Thyroid diseases have effects on cardiovascular system and compensated hypothyroidism (CH) can cause sytolic and diastolic dysfunctions. We aimed to investigate the effects of levothyroxine (LT-4) treatment on cardiac functions in infants with CH. Materials and Methods: Fourty one cases who admitted with elevated TSH levels were included to this study. The cases were divided into three groups. The cases with elevated TSH but in whom CH was excluded were included to first group and those who received treatment to second group. The cases diagnosed as overt hypothyroidism were included to third group. A fourth group was created as a control group. Among these groups, systolic functions and diastolic functions were compared by using M-mode echocardiography and Pulse Wave Tissue Doppler echocardiography. In addition, cardiac intervals including IVCT, IVRT, DT, ET and MPI values were compared. Results: A disturbance was found in cardiac parameters at the beginning in the first, second and third groups. Improvement in diastolic functions was observed in the second group at the end of the third month after the LT-4 treatment. There was no positive change in first group at the end of the third month. In the third group in which thyroid hormone deficiency was more severe than the other two groups, initial systolic and diastolic dysfunction resolved with three months of L-T4 treatment. Conclusion: These results indicate the presence of cardiac involvement with various severity in cases with hypothyroidism and it was noted that L-T4 treatment had an improving effect on cardiac parameters.