Future trials of therapy should concentrate on patients with severe nonthyroidal illness and a high mortality rate. Treatment is directed toward the underlying illness thyroid hormone replacement is not indicated. Diagnosis is based on excluding hypothyroidism. The small number of controlled trials performed to date have shown conflicting results on the cardiovascular effects of triiodothyronine, and none has had the statistical power to address the question of altered mortality. In addition to primary and secondary hypothyroidism, other conditions may cause decreased levels of total T4, such as euthyroid sick syndrome Euthyroid Sick Syndrome Euthyroid sick syndrome is a condition in which serum levels of thyroid hormones are low in patients who have nonthyroidal systemic illness but who are actually euthyroid. Euthyroid sick syndrome is a condition in which serum levels of thyroid hormones are low in patients who have nonthyroidal systemic illness but who are actually euthyroid. Consequently, the use of thyroid hormone therapy in the euthyroid sick syndrome is controversial. It remains unresolved whether the hormone responses in the euthyroid sick syndrome represent part of an adaptive response, which lowers tissue energy requirements in the face of systemic illness, or a maladaptive response, which induces damaging tissue hypothyroidism.
The degree of thyroid function disturbance correlates with disease severity and low levels of thyroid hormones predict a poor prognosis in several illnesses. These thyroid hormone changes may be mediated in part by cytokines or other inflammatory mediators, acting at the level of the hypothalamus and pituitary, the thyroid gland, and the hepatic deiodinase system, as well as on binding of thyroxine to thyroid binding globulin. Abnormalities of thyroid hormone concentrations are seen commonly in a wide variety of nonthyroidal illnesses, resulting in low triiodothyronine, total thyroxine, and thyroid stimulating hormone concentrations.
0 kommentar(er)
