The Relationship Between Hypothyroidism and Cardiac Findings in Children With and Without Down Syndrome

OBJECTIVE
Down syndrome is a genetic syndrome characterized with various dysmorphisms and congenital malformations such as congenital heart diseases. We aimed to evaluate the relationship between Down syndrome, hypothyroidism, and cardiac findings.


METHODS
Thyroid hormone profiles and echocardiographic findings were evaluated. Patients with hypothyroidism and Down syndrome were named group 1; patients with hypothyroidism without Down syndrome group 2 and group 3 was control. The echocardiographic parameters (interventricular septum and left ventricular systolic, diastolic posterior wall thickness, left ventricular end-diastolic diameter, ejection fraction) were indexed to body surface area. Left ventricular mass index and relative wall thickness were calculated. Patients with relative wall thickness equal to or below 0.42 were classified as eccentric hypertrophy or normal geometry, while those over 0.42 as concentric remodeling or concentric hypertrophy.


RESULTS
Thyroid stimulating hormone values of groups 1 and 2 were significantly higher than those of group 3. There were no significant differences for fT4 between the groups. Interventricular septum and left ventricular posterior wall end-diastolic and end-systolic thickness were significantly higher in group 1 than groups 2 and 3. There was no statistically significant difference in left ventricular mass index between groups 1 and 2. In terms of relative wall thickness, 16 out of 29 patients in group 1 were revealed as concentric remodeling, 12 as normal geometry, 1 patient as eccentric hypertrophy. In group 2, 6 patients were revealed as concentric remodeling, 14 as normal geometry. There was no statistically significant difference of left ventricular end-diastolic thickness between 3 groups.


CONCLUSION
Cardiac morphology and functions were significantly affected by hypothyroidism in patients with Down syndrome. Hypertrophy in Down syndrome may be caused by the cellular changes in myocardium.