A screening medical test is one that is performed for someone who has no symptoms; someone who feels fine. The purpose of a screening test is to detect a medical problem early so that treatment can be begun before there is any permanent damage.
Examples of screening tests are screening mammography, screening prostate specific antigen, and screening cholesterol testing (in persons who have no evidence of heart problems).
There is controversy about which medical problems (diseases) should be screened for. The question always is “Will a specific screening medical test in this person who feels fine and has no symptoms benefit him or her?” That is, will the test help find a silent medical problem that treatment can help or will it simply lead to treatment that doesn’t help or that even harms the patient.
And different groups of experts and organizations may have different recommendations on screening for medical problems.
Dr. Mario Skugor, a Cleveland Clinic endocrinologist, recommends that patients be screened for hypothyroidism if:
-A patient has a family history of thyroid disease
-A patient has diabetes or rheumatoid arthritis (annual thyroid blood test—TSH)
-A patient has adrenal insufficiency or other autoimmune disease (annual thyroid blood test– TSH)
-A patient is over the age 60 years (annual thyroid blood test—TSH).
Dr. Skugor states that ideally everyone over the age of 35 years should be tested for hypothyroidism although he agrees it might not be cost-effective. (1)
The American Thyroid Association recommends that every person at age 35 years should have thyroid function test (TSH) performed and that it be repeated every five years. (2)
But the the premiere group of preventive medicine specialists, the US Preventive Services Task Force, makes the following recommendation: (3)
-”The USPSTF concludes the evidence is insufficient to recommend for or against routine screening for thyroid disease in adults.”
The US Preventive Services Task Force bases their conclusion on the following:
“Rationale: The USPSTF found fair evidence that the thyroid stimulating hormone (TSH) test can detect subclinical thyroid disease in people without symptoms of thyroid dysfunction, but poor evidence that treatment improves clinically important outcomes in adults with screen-detected thyroid disease. Although the yield of screening is greater in certain high-risk groups (e.g., postpartum women, people with Down syndrome, and the elderly), the USPSTF found poor evidence that screening these groups leads to clinically important benefits. There is the potential for harm caused by false positive screening tests; however, the magnitude of harm is not known. There is good evidence that over-treatment with levothyroxine occurs in a substantial proportion of patients, but the long-term harmful effects of over-treatment are not known. As a result, the USPSTF could not determine the balance of benefits and harms of screening asymptomatic adults for thyroid disease.”
So the US Preventive Services Task Force concludes that there is no evidence on whether screening for thyroid disease is harmful or beneficial. We just don’t know.
So basically every person who feels healthy and has no known symptoms has to decide for herself/himself if she/he wants to be screened for thyroid disease.
But, it is a totally different matter if a person has any of the many symptoms or abnormal physical examation findings that could be due to thyroid disease. If a person has symptoms or signs that could be due to thyroid disease, then thyroid tests should be done (but since the person has symptoms the thyroid tests are diagnostic not screening). (4)
(1) The Cleveland Clinic Guide to Thyroid Disorders. 2009. Mario Skugor MD.
(2) Ladenson PW, Singer PA, Ain KB, et al. American Thyroid Association guidelines for detection of thyroid dysfunction. Arch Intern Med 2000;160(11):1573-5.
(3) Screening for Thyroid Disease—Recommendation Statement from the US Preventive Services Task Force available at http://www.uspreventiveservicestaskforce.org/3rduspstf/thyroid/thyrrs.htm.
(4) Symptoms of hypothyroidism are discussed in Test Yourself For an Underactive Thyroid Gland (Hypothyroidism) available at http://www.tomwademd.net/2012/04/09/test-yourself-for-an-underactive-thyroid-gland-hypothyroidism/.