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Subclinical hyperthyroidism unrelated to overall, CV mortality
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QUEBEC CITY — The associated health risks for subclinical hyperthyroidism in patients aged at least 65 years are not entirely clear. However, data presented at the 82nd Annual Meeting of the American Thyroid Association suggest that the disease was not linked to overall or cardiovascular mortality.
“[Older patients with subclinical hypothyroidism] They are a group with a high prevalence of subclinical thyroid dysfunction and a high prevalence of comorbidities that make their management more complex,” researcher Anne R. Cappola, MD, ScM, associate professor of medicine at Penn Medicine and physician at the Perelman Center for Advanced Medicine in Philadelphia told Endocrine Today.
Cappola said there are two clinical implications.
“One, thyroid function testing should be repeated in older people with subclinical hyperthyroidism to confirm testing prior to initiating management. Two, older people with subclinical hyperthyroidism are at increased risk of atrial fibrillation,” Cappola said.
The Cardiovascular Health Study (CHS) was used to examine the 5,009 community-dwelling patients aged 65 years and older who were not taking thyroid medications. According to data, the serum thyroid-stimulating hormone and free thyroxine concentrations were measured in banked specimens at visits between 1989 and 1990, 1992 and 1993, and 1996 and 1997.
Within the CHS, researchers identified 70 patients with an average age of 73.7 years (60% women, 24% not white) with subclinical hyperthyroidism based on their first TSH measurement. They studied the persistence, resolution and progression of the disease during a 2- to 3-year period.
Using Cox proportional hazard models, researchers were able to determine the link between subclinical hyperthyroidism and CV risk and total mortality after more than 10 years of follow-up, with 4,194 euthyroid patients used as a reference group.
According to data, of the patients with subclinical hyperthyroidism who participated in follow-up thyroid testing or were taking thyroid medication at the time of follow-up (n=44), 43% persisted; 41% became euthyroid; 5% progressed to the point of overt hyperthyroidism; and 11% began taking thyroid medication.
“Our study provides additional supportive data in both estimates of persistence of subclinical hyperthyroidism and risk of cardiovascular effects,” Cappola said.
Subsequently, the researchers found no association between subclinical hyperthyroidism and overall or CV mortality. – by Samantha Costa
Anne R. Cappola, MD, ScM, can be reached at the Perelman Center for Advanced Medicine, West Pavilion, 4th Floor, 3400 Civic Center Boulevard, Philadelphia, PA 19104; email: acappola@mail.med.upenn.edu.
For more information:
Fortinsky P. O7. Presented at: The American Thyroid Association Annual Meeting; Sept. 19-23, 2012; Quebec City.
Disclosure: The researchers report no relevant financial disclosures.