Table 5. Association of Each Clinical Risk Factor with Final US Assessment.

	P
Age < 20 or > 60	0.007
Gender	0.723
1st degree family history	0.009
Solitary lesion on US	0.777
Serum TSH value
Mean TSH level (mIU/L)	0.001
TSH grade (3 categories)	0.001
TSH grade (2 categories)	0.168

P values from χ²-square test or independent two sample t test. TSH = thyroid stimulating hormone, US = ultrasonography