Thyroid-stimulating hormone levels were associated with free thyroxine/triiodothyronine ratio among healthy, euthyroid adults, according to researchers in South Korea. They also reported that free thyroxine/triiodothyronine ratio, or FT3/FT4, was a better predictive marker for metabolic syndrome than TSH.
Thyroid function and metabolic syndrome in the population-based LifeLines cohort study