Elevated TSH levels common in elderly, but not associated with increased mortality

Annual Meeting of the ATA

INDIAN WELLS, Calif. — Elderly people exhibited slight increases in thyroid-stimulating hormone levels during a 13-year period, yet researchers noted no relationship between these changes and risk for death.

"We have a particular interest in looking at subclinical hypothyroidism and what the clinical implications are further down the line, such as whether or not this is something that needs to be treated," Avantika C. Waring, MD, of the University of California, San Francisco, told ENDOCRINE TODAY. "In the elderly, this is particularly controversial because there are not a lot of data in people aged older than 80 years, and that tends to be a very important demographic nowadays."

To investigate further, Waring and colleagues measured TSH, free thyroxine (T4), total triiodothyronine (T3) and thyroid peroxidase antibodies (TPOAb) in samples obtained between 1992 and 1993 and again between 2005 and 2006 from 1,049 participants (mean age, 85.6 years) enrolled in the Cardiovascular Health Study All-Stars Study. The researchers then calculated overall and annual changes in these thyroid hormones during the 13-year period in participants not receiving thyroid medication.

Eighty-eight percent of these participants were euthyroid at the second visit, with subclinical hypothyroidism emerging as the most common form of thyroid dysfunction (10% of the cohort). From the initial visit to the second examination, the researchers found small, but statistically significant, increases in TSH (0.32 mU/L; P<.01) and free T4 (0.2 ng/dL; P=.01) as well as a 0.23-nmol/L decrease in total T3 (P<.01). The median annual rate of change in TSH among participants not using thyroid medication was 0.017 mU/L per year, the researchers reported, with data suggesting no link between TSH level at the second visit (HR=0.95; 95% CI, 0.89-1.02) or TPOAb status and mortality (HR=1.03; 95% CI, 0.65-1.61) during a median follow-up period of 4.8 years.

"Clinically, this could mean that as people age, they may have an increase in their TSH levels, but it doesn't necessarily signify that they're at a higher risk for death," Waring said. "One interesting finding we observed is that higher free T4 levels in these patients were associated with a greater risk for death. We still don't know what this means clinically because what you would have to do is treat these individuals to find out if altering their thyroid hormone levelsthat would ultimately make a difference. But it was an interesting observation that we didn't expect to find."

Waring also noted that other studies of individuals aged older than 80 years would be beneficial, as well as conducting a randomized trial to see if treatment of high TSH improves outcomes.

For more information:

Waring AC. Poster 111. Presented at: the 81st Annual Meeting of the American Thyroid Association; Oct. 26-30, 2011; Indian Wells, Calif.

Disclosure: Dr. Waring reports no relevant financial disclosures.

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