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Levothyroxine neutral for bone health in subclinical hypothyroidism
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Older adults with subclinical hypothyroidism assigned 1 year of levothyroxine therapy experienced no adverse changes in any bone parameters compared with similar adults assigned placebo, according to findings published in The Journal of Clinical Endocrinology & Metabolism.
In a nested substudy, Elena Gonzalez Rodriguez, MD, PhD, deputy chief of clinic in the department of endocrinology, diabetes and metabolism at University Hospital of Vaud in Lausanne, Switzerland, and colleagues analyzed data from 196 adults aged at least 65 years enrolled in the TRUST trial, a double-blind, placebo-controlled study assessing persistent subclinical hypothyroidism among older adults (mean age, 74 years; 45.4% women; 19.6% had osteoporosis). Researchers randomly assigned participants to levothyroxine with dose titration or placebo with computerized mock-titration. Participants underwent measurements of bone parameters via DXA at baseline and 1-year follow-up. Primary outcomes were 1-year percent changes of bone mineral density, trabecular bone score, and the bone turnover markers C-terminal telopeptide and procollagen type 1 N-terminal propeptide.
In unadjusted analyses, researchers found that BMD percentage changes at 1 year were not statistically different between the levothyroxine and placebo groups at the lumbar spine (0.8% vs. –0.6%; between-group difference, 1.4 percentage points; P = .059). Results were similar for trabecular bone score (between-group difference, –1.3 percentage points; 95% CI, –3.1 to 0.6) and total hip BMD (between-group difference, –0.2 percentage points; 95% CI, –1.1 to 0.1). There was no between-group differences in bone turnover markers at 1 year. Results for all analyses persisted after adjustment for clinical site and sex.
“Our results are reassuring in the context of the large number of individuals with subclinical hypothyroidism treated with levothyroxine, although this trend may change in the view of latest evidence and guidelines,” the researchers wrote. “Only a large long-term, placebo-controlled trial will definitively determine if treatment of subclinical hypothyroidism adversely affects bone health, and to the best of our knowledge such a trial is not ongoing or planned in the near future. Until long-term safety is ascertained, we suggest that physicians who wish to treat subclinical hypothyroidism in their older patients prescribe the lowest thyroxine dose to achieve a clinical response and keep TSH within the normal range.” – by Regina Schaffer
Disclosure: One of the authors reports owning stock in Medimaps Group, the makers of trabecular bone score software.
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