Subclinical hyperthyroidism is defined as a patient having normal free thyroxine (FT4) and total triiodothyronine (T3) levels in conjunction with a thyrotropin (TSH) level persistently below the normal range in the absence of factors known to suppress TSH. Factors that may alter TSH value and thyroid function test results include medications such as corticosteroids and dopamine and clinical conditions to include hypothalamic or pituitary hypofunction and nonthyroid illness.1,2 Nonthyroid illness is a general term that applies to a wide variety of patients who have systemic illness that can result in altered thyroid function test results. In general, the diagnosis of subclinical hyperthyroidism is made in ambulatory outpatients who are not taking medications known to affect thyroid function. The incidence of subclinical hyperthyroidism is approximately 1%.3 The most common causes of endogenous subclinical hyperthyroidism include Graves disease (usually younger patients), multinodular goiter (typically older patients), and solitary autonomous nodules. The discrimination between endogenous hyperthyroidism from exogenous hyperthyroidism is important, since exogenous hyperthyroidism can usually be treated by modulation of the levothyroxine dose. Although the study by Collet et al4 focuses on cardiovascular effects, subclinical hyperthyroidism is also associated with an increased risk of osteopenia and/or osteoporosis, especially in older women, which may improve following treatment of the hyperthyroidism.5 It is controversial whether cognitive function is altered by the presence of subclinical hyperthyroidism.
Thank you for submitting a comment on this article. It will be reviewed by JAMA Internal Medicine editors. You will be notified when your comment has been published. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest*
Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Web of Science® Times Cited: 1
Customize your page view by dragging & repositioning the boxes below.
More Listings atJAMACareerCenter.com >
Users' Guides to the Medical Literature
Clarifying Your Question
Users' Guides to the Medical Literature
Three Examples of Question Clarification
All results at
Enter your username and email address. We'll send you a link to reset your password.
Enter your username and email address. We'll send instructions on how to reset your password to the email address we have on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.