Screening and treatment of thyroid dysfunction: an evidence review for the U.S. Preventive Services Task Force
J. Bruin Rugge, Christina Bougatsos, Roger Chou
Evidence on thyroid screening effects remains inconclusive
Data Sources were MEDLINE and Cochrane databases through July 2014. Studies selected were randomized, controlled trials and observational studies of screening and treatment. One investigator abstracted data, and a second investigator confirmed; two investigators independently assessed study quality. Primary funding source was the Agency for Healthcare Research and Quality.
- No study directly assessed benefits and harms of screening versus no screening.
- For subclinical hypothyroidism (based on thyroid-stimulating hormone levels of 4.1 to 11.0 mIU/L), one fair-quality cohort study found that treatment of subclinical hypothyroidism was associated with decreased risk for coronary heart disease events versus no treatment.
- No study found that treatment was associated with improved quality of life, cognitive function, blood pressure, or body mass index versus no treatment.
- Effects of treatment versus no treatment showed potential beneficial effects on lipid levels, but effects were inconsistent, not statistically significant in most studies, and of uncertain clinical significance (difference, −0.7 to 0 mmol/L [−28 to 0 mg/dL] for total cholesterol levels and −0.6 to 0.1 mmol/L [−22 to 2 mg/dL] for low-density lipoprotein cholesterol levels).
- Treatment harms were poorly studied and sparsely reported. Two poor-quality studies evaluated treatment of subclinical hyperthyroidism but examined intermediate outcomes. No study evaluated treatment versus no treatment of screen-detected, undiagnosed overt thyroid dysfunction.