![]() Parle JV, Franklyn JA, Cross KW, Jones SC, Sheppard MC. Screening for subclinical thyroid dysfunction in nonpregnant adults: a summary of the evidence for the U.S. In: DeGroot LJ, Jameson JL, Burger H, eds. Screening for thyroid disease: an update. Summary of policy recommendations for periodic health examinations. 1998 8:803-13.Ĭommission on Clinical Policies and Research. Subclinical thyroid disease in the elderly. ![]() Epidemiology and prevention of clinical and subclinical hypothyroidism. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey. Vanderpump MP, Tunbridge WM, French JM, Appleton D, Bates D, Clark F, et al. Screening for thyroid disease: recommendation statement. Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH, et al. 1 This committee defined subclinical hypothyroidism as “a serum TSH concentration above the statistically defined upper limit of the reference range when serum free T 4 (FT 4) concentration is within its reference range.” Subclinical hyperthyroidism was defined as “a serum TSH concentration below the statistically defined lower limit of the reference range when serum FT 4 and T 3 concentrations are within their reference ranges.” Based on a series of studies, the panel determined that the reference range for serum TSH is 0.45 to 4.50 μU per mL (0.45 to 4.50 mU per L). In 2002, a scientific review and consensus committee, which included representatives from the American Thyroid Association, the American Association of Clinical Endocrinologists, and the Endocrine Society, convened a panel of experts to define subclinical thyroid disease, review the literature concerning risks and benefits of treatment, and make recommendations about evaluation and population-based screening. ![]() Subclinical hyperthyroid and hypothyroid disease are laboratory diagnoses. There is little evidence that early treatment alters the clinical course. A serum thyroid-stimulating hormone level of less than 0.1 μU per mL is associated with progression to overt hyperthyroidism, atrial fibrillation, reduced bone mineral density, and cardiac dysfunction. There is insufficient evidence that treatment of subclinical hypothyroidism is beneficial. Patients with a serum thyroid-stimulating hormone level greater than 10 μU per mL have a higher incidence of elevated serum low-density lipoprotein cholesterol concentrations however, evidence is lacking for other associations. There is good evidence that subclinical hypothyroidism is associated with progression to overt disease. Most national organizations recommend against routine screening of asymptomatic patients, but screening is recommended for high-risk populations. Subclinical hyperthyroidism is found in approximately 2 percent of the population. The prevalence of subclinical hypothyroidism is about 4 to 8.5 percent, and may be as high as 20 percent in women older than 60 years. The management of subclinical thyroid dysfunction is controversial. Meanwhile, better understanding is needed of the impact of the altered thyroid hormone status on tissue function.Subclinical thyroid dysfunction is defined as an abnormal serum thyroid-stimulating hormone level (reference range: 0.45 to 4.50 μU per mL) and free thyroxine and triiodothyronine levels within their reference ranges. Future trials of therapy should concentrate on patients with severe nonthyroidal illness and a high mortality rate. 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. 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 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |