0
We're unable to sign you in at this time. Please try again in a few minutes.
Retry
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
Retry
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......
Original Investigation |

Falling Threshold for Treatment of Borderline Elevated Thyrotropin Levels—Balancing Benefits and Risks:  Evidence From a Large Community-Based Study

Peter N. Taylor, MSc, MRCP1,2; Ahmed Iqbal, MRCP3; Caroline Minassian, MSc4; Adrian Sayers, MSc2; Mohd S. Draman, MRCP1; Rosemary Greenwood, MSc5; William Hamilton, MD6; Onyebuchi Okosieme, MD, FRCP1; Vijay Panicker, PhD7; Sara L. Thomas, PhD4; Colin Dayan, PhD, FRCP1,3
[+] Author Affiliations
1Thyroid Research Group, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff, United Kingdom
2Department of Social and Community Based Medicine, University of Bristol, Bristol, United Kingdom
3Henry Wellcome Laboratories for Integrative Neurosciences and Endocrinology, University of Bristol, Bristol, United Kingdom
4Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
5University Hospitals Bristol National Health Service Foundation Trust, Bristol, United Kingdom
6University of Exeter Medical School, Exeter, United Kingdom
7Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Australia
JAMA Intern Med. 2014;174(1):32-39. doi:10.1001/jamainternmed.2013.11312.
Text Size: A A A
Published online

Importance  Rates of thyroid hormone prescribing in the United States and the United Kingdom have increased substantially. If some of the increase is due to lowering the thyrotropin threshold for treatment, this may result in less benefit and greater harm.

Objective  To define trends in thyrotropin levels at the initiation of levothyroxine sodium therapy and the risk of developing a suppressed thyrotropin level following treatment.

Design, Setting, Participants, and Exposure  Retrospective cohort study using data from the United Kingdom Clinical Practice Research Datalink. Among 52 298 individuals who received a prescription for levothyroxine between January 1, 2001, and October 30, 2009, we extracted data about the thyrotropin level before levothyroxine therapy initiation, clinical symptoms, and thyrotropin levels up to 5 years after levothyroxine was initiated. We excluded persons who had a history of hyperthyroidism, pituitary disease, or thyroid surgery; those who were taking thyroid-altering medication or if the levothyroxine prescription was related to pregnancy; and those who did not have a thyrotropin level measured within 3 months before the initiation of levothyroxine.

Main Outcomes and Measures  The median thyrotropin level at the time of the index levothyroxine prescription, the odds of initiation of levothyroxine therapy at thyrotropin levels of 10.0 mIU/L or less, and the age-stratified odds of developing a low or suppressed thyrotropin level after levothyroxine therapy.

Results  Between 2001 and 2009, the median thyrotropin level at the initiation of levothyroxine therapy fell from 8.7 to 7.9 mIU/L. The odds ratio for prescribing levothyroxine at thyrotropin levels of 10.0 mIU/L or less in 2009 compared with 2001 (adjusted for changes in population demographics) was 1.30 (95% CI, 1.19-1.42; P < .001). Older individuals and individuals with cardiac risk factors had higher odds of initiation of levothyroxine therapy with a thyrotropin level 10.0 mIU/L or less. At 5 years after levothyroxine initiation, 5.8% of individuals had a thyrotropin level of <0.1 mIU/L. Individuals with depression or tiredness at baseline had increased odds of developing a suppressed thyrotropin level, whereas individuals with cardiac risk factors (eg, atrial fibrillation, diabetes mellitus, hypertension, and raised lipid levels) did not.

Conclusions and Relevance  We observed a trend toward levothyroxine treatment of more marginal degrees of hypothyroidism and a substantial risk of developing a suppressed thyrotropin level following therapy. Large-scale prospective studies are required to assess the risk-benefit ratio of current practice.

Figures in this Article

Sign in

Create a free personal account to sign up for alerts, share articles, and more.

Purchase Options

• Buy this article
• Subscribe to the journal

First Page Preview

View Large
First page PDF preview

Figures

Place holder to copy figure label and caption
Figure 1.
Thyrotropin Levels at the Time of the Index Prescription of Levothyroxine

Dark bars indicate thyrotropin levels less than 4.0 mIU/L; medium bars, 4.0 to 10.0 mIU/L; and light bars, greater than 10.0 mIU/L. Levothyroxine given as levothyroxine sodium.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.
Median Thyrotropin Levels at the Time of the Index Prescription of Levothyroxine and Rate of Index Prescriptions by Year

The annual median thyrotropin level fell during the study period from 8.7 to 7.9 mIU/L. Levothyroxine given as levothyroxine sodium.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 3.
Thyrotropin Levels After Initiation of Levothyroxine

A, Undertreated. B, Overtreated. Levothyroxine given as levothyroxine sodium.

Graphic Jump Location

Tables

References

Correspondence

CME
Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
Submit a Comment

Multimedia

Some tools below are only available to our subscribers or users with an online account.

Web of Science® Times Cited: 5

Sign in

Create a free personal account to sign up for alerts, share articles, and more.

Purchase Options

• Buy this article
• Subscribe to the journal

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Collections
PubMed Articles
Jobs
brightcove.createExperiences();