The full content of Annals is available to subscribers

Subscribe/Learn More  >
Articles |

Decreased Levothyroxine Requirement in Women with Hypothyroidism during Androgen Therapy for Breast Cancer

Baha M. Arafah, MD
[+] Article, Author, and Disclosure Information

From the University Hospitals of Cleveland, Cleveland, Ohio. Requests for Reprints: Baha M. Arafah, MD, Division of Clinical and Molecular Endocrinology, University Hospitals of Cleveland, 11100 Euclid Avenue, Room 3128 Lakeside, Cleveland, OH 44106. Acknowledgments: The author thanks all referring physicians and the nursing staff at the Clinical Research Center, Cancer Center, and the outpatient facility for their help in conducting the study; Dr. F. Ismail-Beigi for reviewing the manuscript; and Robert Meyers for technical assistance.

Copyright ©2004 by the American College of Physicians

Ann Intern Med. 1994;121(4):247-251. doi:10.7326/0003-4819-121-4-199408150-00002
Text Size: A A A

Objective: To determine the effects of androgen administration on measures of thyroid function and thyroid hormone replacement doses in women with breast cancer.

Design: Consecutive patients with metastatic, hormone-dependent breast cancer who were eligible for androgen treatment.

Interventions: Androgen therapy (fluoxymesterone, 10 mg orally twice daily) was continued for as long as it was effective in controlling tumor growth.

Patients: 7 patients with no known thyroid disease and 4 others receiving long-term treatment for hypothyroidism.

Measurements: Serum levels of total and free thyroxine (T4), thyroid-stimulating hormone (TSH), and T4-binding globulin were determined before and every 4 weeks after androgen therapy was initiated.

Results: Within 4 weeks of androgen administration to the seven patients without thyroid disease, serum levels of total T4 and T4-binding globulin decreased (P < 0.001), whereas the calculated free thyroxine index and measured free hormone levels remained unchanged. Six to 12 weeks after androgen therapy was discontinued, all seven patients remained clinically euthyroid, and serum levels returned to baseline values.

In contrast, clinical hyperthyroidism developed shortly after androgen was administered to four patients who received long-term thyroid hormone replacement therapy. Within 4 weeks of treatment, the serum free T4 level increased in each of the four patients, whereas the TSH level decreased. Thyroid hormone doses had to be reduced by 25% to 50% to maintain euthyroidism.

Conclusions: The study documents the reversible effects of androgens on thyroid hormone levels and indicates the need to reduce thyroid replacement doses in women during androgen therapy. Monitoring thyroid hormone levels in patients receiving replacement therapy and perhaps in those with autonomous thyroid function is necessary after androgen therapy.


Grahic Jump Location
Figure 1.
Serial measurements of total thyroxine (T4) and free thyroxine (fT4), T4-binding globulin (TBG), triiodothyronine resin uptake (T3RU), free thyroxine index (fT4I), and thyroid-stimulating hormone (TSH) levels obtained during androgen administration to seven women with no history of thyroid disease.PP

Each point represents the mean ±SD (error bars). * = < 0.001 compared with levels before treatment. + = < 0.001 compared with values before treatment.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels in four women who received long-term treatment for primary hypothyroidism measured before, during, and after androgen therapy for breast cancer.

The upper portion of each graph shows the levothyroxine dose used; the arrows indicate the beginning and duration of androgen therapy. Levothyroxine dose was not altered in patient 1 but was reduced during androgen administration to patients 2, 3, and 4 to maintain euthyroidism.

Grahic Jump Location




Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).


Submit a Comment/Letter
Submit a Comment/Letter

Summary for Patients

Clinical Slide Sets

Terms of Use

The In the Clinic® slide sets are owned and copyrighted by the American College of Physicians (ACP). All text, graphics, trademarks, and other intellectual property incorporated into the slide sets remain the sole and exclusive property of the ACP. The slide sets may be used only by the person who downloads or purchases them and only for the purpose of presenting them during not-for-profit educational activities. Users may incorporate the entire slide set or selected individual slides into their own teaching presentations but may not alter the content of the slides in any way or remove the ACP copyright notice. Users may make print copies for use as hand-outs for the audience the user is personally addressing but may not otherwise reproduce or distribute the slides by any means or media, including but not limited to sending them as e-mail attachments, posting them on Internet or Intranet sites, publishing them in meeting proceedings, or making them available for sale or distribution in any unauthorized form, without the express written permission of the ACP. Unauthorized use of the In the Clinic slide sets will constitute copyright infringement.


Buy Now for $32.00

to gain full access to the content and tools.

Want to Subscribe?

Learn more about subscription options

Related Articles
Related Point of Care
Topic Collections
PubMed Articles
Forgot your password?
Enter your username and email address. We'll send you a reminder to the email address on record.