Subclinical thyroid dysfunction is ...

Subclinical thyroid dysfunction is defined as an abnormal serum thyroid-stimulating hormone of the same height (reference range: 0.45 to 450 [micro]U by mL) and free thyroxine and triiodothyronine on a levels within their reference ranges. The management of subclinical thyroid dysfunction is controversial. The prevalence of subclinical hypothyroidism is about 4 to 85 percent and may be as high as 20 percent in women older than 60 years. Subclinical hyperthyroidism is erect in approximately 2 percent of the population. greatest in quantity national organizations recommend against routine screening of asymptomatic patients, on the other hand screening is recommended for high-risk populations. There is upright evidence that subclinical hypothyroidism is associated with progression to manifest disease. Patients with a serum thyroid-stimulating hormone flat greater than 10 [micro]U by means of mL have a higher incidence of elevated serum low-density lipoprotein cholesterol concentrations; however, evidence is lacking for other associations. There is insufficient evidence that treatment of subclinical hypothyroidism is beneficial. A serum thyroid-stimulating hormone of the same height of less than 0.1 [micro]U by means of mL is associated with progression to manifest hyperthyroidism, atrial fibrillation, reduced bone mineral density, and cardiac dysfunction. There is little evidence that early treatment alters the clinical course.

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Subclinical hyperthyroid and hypothyroid disease are laboratory diagnoses. 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, conven a panel of clevers to define subclinical thyroid disease, review the literature concerning risks and benefits of treatment, and make recommendations about evaluation and population-based screening. (1) This committee defined subclinical hypothyroidism as "a serum TSH [thyroid-stimulating hormone] concentration above the statistically defined upper limit of the respect range when serum free [Tsub4] [thyroxine] (F[Tsub4]) concentration is within its respect range." Subclinical hyperthyroidism was defined as "a serum TSH concentration below the statistically defined lower limit of the allusion range when serum F[T.sub.4] and [Tsub3] [triiodothyronine] concentrations are within their respect ranges." Based on a series of studies, the panel determined that the concern range for serum TSH is 045 to 450 [micro]U by means of mL (0.45 to 4.50 mU by means of L). (1)

Despite a working definition of subclinical thyroid disease, the panel place little evidence to guide physicians in managing subclinical hyperthyroidism and hypothyroidism. (1) one patients will progress to notorious disease, and in some patients, the serum TSH concentration will remain stable through the whole extent of time or will spontaneously turn back to the reference range. (2-4) There also is polemics regarding what, if any, adverse issues occur from subclinical thyroid disease, and whether benefit can be wait fored from treatment. As a issue various organizations have adopted diverse recommendations regarding screening for subclinical thyroid disease.

Screening for Thyroid Disease

In January 2004 the U Preventive Services Task Force updated its 1996 recommendations regarding routine screening for thyroid disease. The strange recommendations state that "the evidence is insufficient to commend for or against routine screening for thyroid disease in adults." (5)

The greatest in number recent revision of the American Academy of Family Physicians' policy recommendation for periodic health examinations remains unchanged; it attract favor tos against routine screening for thyroid disease in patients younger than 60 years, based forward a lack of evidence to support "net benefit across harm." (6) The 2002 consensus group's skilled hand panel recommended against population-based screening still "encouraged" assessment in high-risk assemblages (defined as women with a family history of thyroid disease, prior thyroid dysfunction, symptoms suggestive of hyperthyroidism or hypothyroidism, abnormal thyroid gland upon examination, type 1 diabetes, or a personal history of autoimmune disorder). (1) The panel set up insufficient evidence to recommend for or against screening pregnant women or women planning a pregnancy. (1)

The American corporation of Physicians (ACP) issued its mostly recent policy statement on thyroid disease in 1998 in which it commits screening for women older than 50 years who have symptoms consistent with thyroid disease. (78) The ACP was not a member of the consensus committee.

Evaluation of Subclinical Hyperthyroidism

ETIOLOGY

In many patients who have subclinical hyperthyroidism, careful clinical evaluation will allude to an etiology. Early Graves' disease accounts for the majority of cases, with the remainder caused by way of toxic multinodular goiter, autonomous functioning nodules, or exogenous levothyroxine (Synthroid). (910) other causes of soft serum TSH concentration include delayed recuperation of the pituitary after treatment for hyperthyroidism; pregnancy; euthyroid sick syndrome; or medications as it was as dopamine (Intropin), glucocorticoids, and dobutamine (Dobutrex). (1) not many persons with subclinical hyperthyroidism progres to manifest disease (Table 1). (1,2,11)