Currently available evidence is insufficient to recommend for or against screening for thyroid dysfunction in asymptomatic adults and women who are not pregnant, according to newly updated recommendations.
The researchers and UPSTF, acknowledged that thyroid screening can identify patients who have subclinical thyroid dysfunction or undiagnosed overt thyroid disease but said more evidence is needed to understand the effects of treatment for these problems. Read more for complete description and understanding Thyroid Dysfunction..FACTS
Excerpts in this post are from: March 2015 Task Force FINAL Recommendation
What is thyroid dysfunction?
Thyroid dysfunction is a range of disorders related to the thyroid gland. (A gland is an organ that makes chemical substances for the body.)
The thyroid is a butterfly-shaped gland in the neck that produces two hormones. These hormones control the rate of many activities in the body, such as how fast a person burns calories or how fast the heart beats.
Facts about the Thyroid and Thyroid Dysfunction
The thyroid gland works together with another gland in the body, the pituitary gland. The pituitary gland, a small gland in the brain, controls how much of two specific hormones are produced by the thyroid. The pituitary does this by releasing its own hormone, which is known as thyroid-stimulating hormone (TSH). The pituitary makes more TSH when levels of thyroid hormones in the blood are low. The pituitary makes less TSH when thyroid hormone levels are high.
Thyroid dysfunction refers to a range of changes in TSH levels, either above or below a pre-set level defined as “normal.” These changes include:
Subclinical hypothyroidism: The TSH level is above the “normal” level and thyroid hormone levels are normal.
Overt hypothyroidism: The TSH level is above “normal” and thyroid hormone levels are too low.
Subclinical hyperthyroidism: The TSH level is below “normal” and thyroid hormone levels are normal.
Overt hyperthyroidism: The TSH level is below “normal” and thyroid hormone levels are too high.
People with thyroid dysfunction often do not have obvious symptoms. When symptoms do occur, they can include fatigue orhyperactivity, gaining or losing weight, or feeling cold or hot. However, these symptoms are very general. They can occur in many kinds of health conditions as well as in response to common situations people face in their daily lives, such as stress.
Thyroid disease happens when people with overt hypo- or hyperthyroidism have levels of thyroid hormones and TSH that stay above or below normal for a long time. Most importantly, these individuals also have ongoing symptoms that cannot be explained by any other cause. This final recommendation applies only to people with thyroid dysfunction, not thyroid disease.
Screening for Thyroid Dysfunction
Screening is done with a blood test that measures the amount of TSH in the blood. This test is known as a serum TSH test. Depending on the initial test results, a follow-up test may be needed.
The test can accurately identify a person’s TSH level, but health care professionals do not always agree about what level is “abnormal,” because abnormal levels may be different for different groups. For example, an abnormal level may be different for an older person than for a younger person. Also, abnormal results on a TSH test can be caused by non-thyroid illnesses or medications. Abnormal levels can even return to normal on their own.
Potential Benefits and Harms of Screening for Thyroid Dysfunction
The Task Force reviewed studies on the potential benefits and harms of screening for thyroid dysfunction in adults who are not pregnant and who do not show signs or symptoms of the condition. They did not find evidence on whether this screening has long-term health benefits.
The Task Force also did not find direct evidence about the potential harms of thyroid screening. However, potential harms can include false-positive test results (a result that says a condition exists when, in fact, it does not) and overtreatment (treating an abnormal TSH level that may return to normal on its own or that would have never caused health problems on its own).
The Final Recommendation on Screening for Thyroid Dysfunction: What Does It Mean?
Here is the Task Force’s final recommendation on screening for thyroid dysfunction. It is based on the quality and strength of the evidence about the potential benefits and harms of screening for this purpose. Task Force recommendation grades are explained in the box at the end of this fact sheet.