CLINICAL THYROIDOLOGY FOR THE PUBLIC
A publication of the American Thyroid Association
Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID BLOOD TESTS
Thyroid function tends to remain stable in those without risk factors for hypothyroidism or hyperthyroidism
BACKGROUND
Thyroid function screening is usually done by measuring a TSH blood test. This test is able to confirm that the thyroid is making a normal amount of thyroid hormone, and is thus neither underactive (a condition known as hypothyroidism) or overactive (a condition known as hyperthyroidism). Several medical societies recommend measuring a TSH as part of routine health examinations, while others have found that it may not be worth the cost of doing it in everyone.
If a person has certain risk factors, the chance of developing hypothyroidism or hyperthyroidism is higher than in the general population. One such risk factor is having high blood levels of TPO antibodies. This study was performed to see how stable TSH blood tests are in adults with few risk factors for hypothyroidism or hyperthyroidism. The results can help guide often TSH blood tests should be measured in adults as part of routine health examinations.
THE FULL ARTICLE TITLE:
Rosario PW and Calsolari MR. 2018 Serum TSH level stability after 5 years in euthyroid adults at low risk for thyroid dysfunction. Arch Endocrinol Metab. May 17. pii: S2359-39972018005002003. doi: 10.20945/2359-3997000000037.
SUMMARY OF THE STUDY
This was a study of 1,426 adults living in Brazil who had no risk factors for having hypothyroidism or hyperthyroidism. All adults had a blood TSH level measured at baseline and again five years later. At the first sampling, over 96% had a normal TSH level. Of these, over 99% remained in the normal range five years later. All of the results were unchanged regardless of the individuals’ gender or age.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
In adults with no significant risk factors for developing hypothyroidism or hyperthyroidism and an initial TSH blood test in the normal range, it is unlikely to be abnormal if checked again five years later. The researchers suggest that in these individuals, repeating TSH screening within this time interval may not be necessary.
— Angela M. Leung, MD, MSc
ATA THYROID BROCHURE LINKS
Thyroid Function Tests: https://www.thyroid.org/thyroid-function-tests/
Hypothyroidism (Underactive): https://www.thyroid.org/hypothyroidism/
Hyperthyroidism (Overactive): https://www.thyroid.org/hyperthyroidism/
ABBREVIATIONS & DEFINITIONS
TSH: Thyroid stimulating hormone (TSH) is produced by the pituitary gland and is important for regulating thyroid function. It is also the best screening blood test to determine if the thyroid is functioning normally.
TPO antibodies: These are antibodies that attack the thyroid instead of bacteria and viruses. They are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.
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