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Screening for and Treatment of Thyroid Dysfunction

An Evidence Review for the U.S. Preventive Services Task Force

Evidence Syntheses, No. 118

Investigators: , MD, , MPH, and , MD.

Author Information
Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 15-05217-EF-1

Structured Abstract


Screening may lead to detection and treatment of asymptomatic subclinical thyroid dysfunction or undiagnosed overt thyroid disease, potentially resulting in improved clinical outcomes.


To update a 2004 review on screening for thyroid disease for the U.S. Preventive Services Task Force (USPSTF), expanded to include undiagnosed overt thyroid disease.

Data Sources:

We searched Ovid MEDLINE, the Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews from 2002 to July 2014 for subclinical hypothyroidism and hyperthyroidism, and without a prior date limitation for overt thyroid disease. Searches on electronic databases were supplemented by reviews of reference lists.

Study Selection:

Randomized, controlled trials and controlled observational studies on the effects of screening for or treatment of subclinical or overt thyroid disease on clinical and intermediate outcomes.

Data Extraction:

Information regarding the population, setting, treatments, and outcomes was abstracted. The quality of each study was assessed using the standard USPSTF criteria.

Data Synthesis (Results):

No study directly assessed the benefits and harms of screening versus no screening. For subclinical hypothyroidism (thyroid-stimulating hormone [TSH] levels of 4 to 11 mIU/L), one fair-quality cohort study found that treatment of subclinical hypothyroidism was associated with decreased risk for coronary heart disease events versus no treatment. No studies found that treatment was associated with improved quality of life, cognitive function, blood pressure, or body mass index versus no treatment. Effects of treatment versus no treatment showed potential beneficial effects on lipid levels, but effects were inconsistent, not statistically significant in most studies, and of uncertain clinical significance (difference, -28 to 0 mg/dL for total cholesterol [nine studies] and -22 to 2 mg/dL for low-density lipoprotein cholesterol [10 studies]). Harms of treatment were poorly studied and sparsely reported. Two studies evaluated treatment of subclinical hyperthyroidism, but they were poor-quality and examined intermediate outcomes. No studies evaluated treatment versus no treatment for screen-detected, undiagnosed overt thyroid disease.


We did not include non-English–language articles. None of the eligible studies were conducted in the United States. All studies were small and of short duration. Studies used varying TSH values to define subclinical disease and varying doses of thyroxine treatment. Few treatment studies were conducted in screen-detected populations.


Although screening can identify patients with subclinical thyroid dysfunction and undiagnosed overt thyroid disease, direct evidence on the benefits and harms of screening remains unavailable. More research is needed to understand how the effects of treatment of subclinical hypothyroidism on lipid parameters impacts clinical outcomes, and to determine the effects of identification and treatment of subclinical hyperthyroidism and undiagnosed overt thyroid disease.


Acknowledgments: The authors would like to thank AHRQ Medical Officers Aileen Buckler, MD, MPH, and Jennifer Croswell, MD, MPH, as well as current and former members of the U.S. Preventive Services Task Force who contributed to topic deliberations. In addition, the authors thank Raj Sehgal, MD, Paul Gorman, MD, Mark Helfand, MD, MPH, Howard Balshem, MS, and Rose Campbell, MLS, authors of a Comparative Effectiveness Review on this topic, on which this report is largely based.

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services1, Contract No. HHSA-290-2007-10057-I. Prepared by: Pacific Northwest Evidence-based Practice Center2

Suggested citation:

Rugge JB, Bougatsos C, Chou R. Screening for and Treatment of Thyroid Dysfunction: An Evidence Review for the U.S. Preventive Services Task Force. Evidence Synthesis No. 118. AHRQ Publication No. 15-05217-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2014.

This report is based on research conducted by the Pacific Northwest Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. HHSA-290-2007-10057-I). The findings and conclusions in this document are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help health care decisionmakers—patients and clinicians, health system leaders, and policymakers, among others—make well informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information (i.e., in the context of available resources and circumstances presented by individual patients).

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.


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Bookshelf ID: NBK285869PMID: 25927133


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