Association between subclinical hypothyroidism and Sasang constitution in a Korean population.

Serum thyroid-stimulating hormone screening of asymptomatic individuals to diagnose subclinical hypothyroidism remains controversial. We evaluated the potential role of Sasang constitutional discrimination and ryodoraku testing as an alternative and complementary diagnostic tool for subclinical hypothyroidism. Among 1,105 potential subjects, 1,073 were included in this study. Of these, 134 subjects had subclinical hypothyroidism (SCH) and 939 were healthy (euthyroid; EU) control subjects. Blood parameters, including serum thyroid hormone levels, were measured. We classified the participants into the four Sasang constitutional types, Taeyang-type individuals, Taeeum-type individuals, Soyang-type individuals and Soeum-type individuals, and measured their ryodoraku scores (RS). The mean levels of free thyroxine (FT4), glucose, red blood cells and hematocrit in the SCH group were significantly lower compared to those in the EU group (p<0.0183, p=0.0006, p=0.0162 and p=0.0224, respectively). The mean FT4 level of the Soeum-type SCH patients was significantly lower compared to the Soeum-type EU patients (p=0.0423). The total RS was significantly higher in the Taeeum-type SCH patients (p=0.0253) and lower in the Soeum-type SCH patients (p=0.0094) compared to controls. Ryodoraku testing and Sasang constitutional discrimination have the potential to serve as alternative and complementary diagnostic tools for subclinical hypothyroidism.