Echocardiographyc features in resistance to thyroid hormone
Serafino Lio, Alfredo Danese & Ignazio Roiter
Resistance to thyroid hormone (RTH) is a rare dominantly inherited condition of impaired tissue responsiveness to thyroid hormones. Different tissue may exhibit variable degree of resistance and clinical presentation probably depending on the heterogeneity of factors that modulate the isoform of thyroid hormone receptor (THR). The heart shows different isoforms of THR and few data is reported on the cardiac functionally effects of the phenotypic heterogeneity; echocardiography is considered an accurate non-invasive technique for the evaluation of cardiac function. We report the data of three patients with RTH. Two of these is father (pt no. 1) and the only child (pt no. 2) of 59- and 20-year-old, respectively; the third patient (pt no. 3) is a male of 69-year-old. The pt no. 1 and no. 2 revealed a mutation of exon 8-codon 268 of THRβ-1-gene whereas the pt no. 3 is wild-type. None are positive for thyroid autoantibodies. The other principal data were reported in Table.
|Pt no. 1||Pt no. 2||Pt no. 3|
|Pulse rate||Atrial fibrillation||Sinusal rhythm||Atrial fibrillation|
|LV ejection fraction %||56||62||66|
|LV shortening fraction %||31||38||37|
|Valvular abnormality||Fibrosis annulus M||Thickening LAM||Normal|
|Insufficiency M A||Insufficiency M|
|Insufficiency T||Thickening A|
|LV, left ventricle; M, mitral; A, aorta; LAM, anterior mitralic lemb; T, tricuspid.|
In conclusion, in RTH the cardiac abnornmality it doesnt seem only related with mutation but probably also with duration of the condition. In fact is evident an intrafamilial and phenotipic heterogeneity of cardiac manifestation Pulmonary hypertension, shows only in pt no. 1 and previous reported in hyperthyroidism, is probably related to the duration of the disease.