Authors say findings may be due to relative excess of thyroid hormone even when treatment is targeted to reference range goals
By Lori Solomon HealthDay Reporter
MONDAY, Nov. 25, 2024 (HealthDay News) — Levothyroxine (LT4) use is associated with longitudinal loss of bone mass and density in older adults, according to a study scheduled to be presented at the annual meeting of the Radiological Society of North America, held from Dec. 1 to 5 in Chicago.
Elena Ghotbi, M.D., from the Johns Hopkins University School of Medicine in Baltimore, and colleagues examined whether LT4 use and higher thyroid hormone levels within the reference range are associated with greater bone loss over time in older adults. The analysis included data from participants (aged 65 years and older) in the Baltimore Longitudinal Study of Aging (81 LT4 users and 364 propensity-matched nonusers).
The researchers found that during a median follow-up of 6.3 years, LT4 use was associated with greater longitudinal loss of total body bone mass (beta, −6.53) and total body bone density (beta, −0.0014). With an increasing tertile of average free thyroxine, the association was stronger.
“Longitudinal loss of bone mass and density was greater among euthyroid LT4 users,” the authors write. “The more pronounced effects at higher levels of free thyroxine suggest that LT4 use may be associated with a relative excess of thyroid hormone in some older adults on therapy, even with thyroid-stimulating hormone levels within the reference range.”
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