Subclinical Hyperthyroidism, Should it be Treated?


Subclinical Hyperthyroidism (SCHT) is applied to patients with normal levels of free T4 and T3, but who have undetectable levels of TSH. The long term effects are uncertain. Data is now available that suggests that people over 60 with SCHT have a higher risk of atrial fibrillation (rapid heart rate).

Biondi and colleagues recently presented the results of heart studies in 23 subjects with SCHT caused by underlying thyroid nodular disease and 30 controls. The SCHT subjects showed increases in 24-hour heart rate and left ventricular mass. In contrast to other patients with SCHT from too much L-thyroxine therapy, these subjects did not have higher rates of premature atrial contractions.

The study provides additional evidence that SCHT may be associated with abnormal cardiac function and clinical heart disease and may warrant treatment. Once again further study is necessary. There appears to be a narrow corridor of normal thyroid function. Another reason to measure more than just TSH to determine thryoid function.

For More Information: 1999 Scientific Program and full Abstract Listing in PDF for 72nd Annual Meeting of the American Thyroid Association (This is a pdf file and requires Adobe Acrobat Reader to download and read. The sections pertaining to SCHT are Program #238, 271, and 276)

The copyright of the article Subclinical Hyperthyroidism, Should it be Treated? in Thyroid Disease is owned by Keri. Permission to republish Subclinical Hyperthyroidism, Should it be Treated? in print or online must be granted by the author in writing.

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