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The evidence for a narrower thyrotropin reference range is compelling.
Leonard Wartofsky1, Richard A Dickey
1Department of Medicine, Washington Hospital Center, 110 Irving Street NW, Washington, D.C. 20010-2975, USA. leonard.wartofsky@medstar.net
The Journal of Clinical Endocrinology and Metabolism
|September 9, 2005
Summary
New TSH assay methods reveal that previously accepted thyroid stimulating hormone (TSH) reference ranges are invalid. A true normal TSH range is critical for accurate thyroid disease diagnosis and management.
Area of Science:
- Endocrinology
- Clinical Chemistry
- Thyroidology
Background:
- Controversy exists regarding management of subclinical thyroid dysfunction.
- Previously accepted TSH reference ranges are now considered invalid.
- Improved TSH assays and contaminated reference populations necessitate reevaluation.
Purpose of the Study:
- To address the controversy surrounding subclinical thyroid disease management.
- To redefine the normal reference range for TSH.
- To highlight the implications of a revised TSH range for thyroid disease screening and treatment.
Main Methods:
- Analysis of data from highly sensitive TSH assays.
- Evaluation of reference populations for thyroid dysfunction.
- Comparison of TSH levels in diverse ethnic groups, including African-Americans.
Main Results:
- More than 95% of normal individuals have TSH levels below 2.5 mU/liter.
- Higher TSH values in reference populations likely indicate underlying thyroid dysfunction.
- African-Americans exhibit a mean TSH of 1.18 mU/liter, suggesting a true normal mean.
Conclusions:
- Previously accepted TSH reference ranges are no longer valid.
- A revised, more precise TSH normal range is essential.
- Accurate TSH ranges are crucial for effective screening and treatment of thyroid disorders, especially subclinical disease.