Design: To assess whether and to what extent administration of L-T4 is able to modify systolic and diastolic function in patients with subclinical hypothyroidism and in subjects with autoimmune thyroiditis and normal serum TSH. Methods: We studied 26 patients with classical Hashimoto's thyroiditis [18 with increased serum TSH (N3 mU/ml — Group A), and 8 with normal serum TSH (b3 mU/ml) — Group B]; a third group (C) included 13 healthy controls. All subjects underwent Pulsed Wave Tissue Doppler Imaging (PWTDI) to accurately quantify the global and regional left ventricular function. Results: In both groups A and B we confirmed a significant impairment of systolic ejection ( pb0.001 and pb0.05, respectively), a delay in diastolic relaxation ( pb0.001 and pb0.05, respectively) and a decrease in the compliance to the ventricular filling ( pb0.05). Administration of 50 μg/day of L-T4 produced a progressive reduction of serum TSH (within the normal range) and normalization of all PWTDI parameters, which began after 6 months and finished after 12 months. Conclusion: Our data confirm previous evidence that subclinical hypothyroidism is associated with a cardiac dysfunction, even when this is very mild (i.e. with serum TSH still comprised in the normal range), and show that these abnormalities are reversible with L-T4 replacement therapy.
Cardiac effects of L-thyroxine administration in borderline hypothyroidism
MARIOTTI, STEFANO;DEIDDA, MARTINO;MERCURO, GIUSEPPE
2008-01-01
Abstract
Design: To assess whether and to what extent administration of L-T4 is able to modify systolic and diastolic function in patients with subclinical hypothyroidism and in subjects with autoimmune thyroiditis and normal serum TSH. Methods: We studied 26 patients with classical Hashimoto's thyroiditis [18 with increased serum TSH (N3 mU/ml — Group A), and 8 with normal serum TSH (b3 mU/ml) — Group B]; a third group (C) included 13 healthy controls. All subjects underwent Pulsed Wave Tissue Doppler Imaging (PWTDI) to accurately quantify the global and regional left ventricular function. Results: In both groups A and B we confirmed a significant impairment of systolic ejection ( pb0.001 and pb0.05, respectively), a delay in diastolic relaxation ( pb0.001 and pb0.05, respectively) and a decrease in the compliance to the ventricular filling ( pb0.05). Administration of 50 μg/day of L-T4 produced a progressive reduction of serum TSH (within the normal range) and normalization of all PWTDI parameters, which began after 6 months and finished after 12 months. Conclusion: Our data confirm previous evidence that subclinical hypothyroidism is associated with a cardiac dysfunction, even when this is very mild (i.e. with serum TSH still comprised in the normal range), and show that these abnormalities are reversible with L-T4 replacement therapy.
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