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Levothyroxine fails to improve quality of life, thyroid-related symptoms in subclinical hypothyroidism
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Adults with subclinical hypothyroidism assigned to levothyroxine therapy for at least 3 months experienced no improvements in general quality of life or thyroid-related symptoms vs. similar patients assigned to placebo or no treatment, according to findings from a meta-analysis published in JAMA.
“Most patients with subclinical hypothyroidism do not require levothyroxine treatment,” Martin Feller, MD, MSc, scientific research coordinator at the University of Bern, Switzerland, told Endocrine Today. “In this meta-analysis of 21 randomized clinical trials, we observed no benefit of levothyroxine therapy, when compared with placebo, regarding general quality of life, thyroid-related symptoms, depressive symptoms, fatigue, cognitive function, blood pressure or BMI.”
Feller and colleagues analyzed data from 21 randomized clinical trials comparing levothyroxine therapy with placebo or no therapy in 2,192 adults with subclinical hypothyroidism, defined as a thyrotropin level above the reference range in combination with a free thyroxine level within the reference range. Study sizes ranged from 20 to 737 participants (mean age, 32 to 74 years), with percentages of women ranging from 46% to 100%. Seven studies included information about hypothyroid symptoms at baseline, with the burden of symptoms defined as mild to moderate. Studies reported quantitative data for general quality of life and/or thyroid-related quality of life, depressive symptoms, fatigue, cognitive function, pain, muscle strength, BP, BMI, cardiovascular events, mortality or adverse events. Differences in clinical scores were transformed into standardized mean differences (SMDs), with positive values indicating benefit for thyroid hormone therapy (0.2, 0.5 and 0.8 for small, moderate and large effects, respectively). Researchers used random-effects models for meta-analysis.
Across studies, duration of therapy ranged from 3 to 18 months, with mean thyrotropin levels among treated participants ranging from 0.5 mIU/L to 3.7 mIU/L.
In studies assessing general quality of life (n = 796), researchers found that levothyroxine therapy was not associated with benefit (SMD, –0.11; 95% CI, –0.25 to 0.03). A similar lack of benefit with levothyroxine was observed when analyzing studies that assessed thyroid-related symptoms (n = 858; SMD, 0.01; 95% CI, –0.12 to 0.14). Risk of bias was low across studies; however, quality of evidence was considered moderate for symptoms of depression, fatigue, cognitive function and adverse effects and low for CV events and mortality, according to the researchers.
Fuller said several questions remain open after conducting the analysis, including whether levothyroxine therapy could reduce CV events or if levothyroxine could benefit a minority of patients with subclinical hypothyroidism and a thyrotropin level greater than 10 mIU/L or subclinical hypothyroidism with severe symptoms.
“The studies we analyzed in the meta-analysis had too short a follow-up to inform about cardiovascular events, and the studies had insufficient data regarding the burden of hypothyroid symptoms at baseline,” Feller said.
In an analysis published online in The New England Journal of Medicine in April 2017 and reported by Endocrine Today, researchers found that levothyroxine treatment did not significantly improve hypothyroid symptoms score or tiredness score in older adults with subclinical hypothyroidism. In the analysis of clinical laboratory and general practice databases and records on 737 adults with persisting subclinical hypothyroidism randomly assigned to levothyroxine or placebo, researchers observed no differences between the two groups for hypothyroid symptoms score or tiredness score at 12 months. – by Regina Schaffer
For more information:
Martin Feller, MD, MSc, can be reached at the Department of General Medicine, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland; email: martin.feller@insel.ch.
Disclosure: Feller reports no relevant financial disclosures.
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