Subclinical hypothyroidism (sHT) affects 5–15% of the general population; however, the need of lifelong L-T4 therapy is still controversial. As myocardium is a main target of thyroid hormone action, we investigated whether sHT induces cardiovascular alterations. Twenty sHT patients were randomly assigned to receive placebo or L-T4 therapy and were followed for 1 yr. Patients had a significantly higher isovolumic relaxation time (3.1 6 0.5 vs. 2.6 6 0.6; P , 0.03), peak A (0.77 6 0.16 vs. 0.56 6 0.13 m/s; P , 0.01), and preejection/ejection time (PEP/ET) ratio (0.7260.05 vs. 0.576 0.06; P , 0.03) and a lower CVI (P , 0.0001) than controls. In conclusion, sHT affects both myocardial structure and contractility. These alterations may be reversed by L-T4 therapy.
Effect of Levothyroxine on cardiac function and structure in subclinical hypothyroidism: a double blind, placebo-controlled study
DI BELLO, VITANTONIO;MONZANI, FABIO;
2001-01-01
Abstract
Subclinical hypothyroidism (sHT) affects 5–15% of the general population; however, the need of lifelong L-T4 therapy is still controversial. As myocardium is a main target of thyroid hormone action, we investigated whether sHT induces cardiovascular alterations. Twenty sHT patients were randomly assigned to receive placebo or L-T4 therapy and were followed for 1 yr. Patients had a significantly higher isovolumic relaxation time (3.1 6 0.5 vs. 2.6 6 0.6; P , 0.03), peak A (0.77 6 0.16 vs. 0.56 6 0.13 m/s; P , 0.01), and preejection/ejection time (PEP/ET) ratio (0.7260.05 vs. 0.576 0.06; P , 0.03) and a lower CVI (P , 0.0001) than controls. In conclusion, sHT affects both myocardial structure and contractility. These alterations may be reversed by L-T4 therapy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
