Table 1. Time trend of the detection rate of PTC, FTC and MTC in all thyroidectomy.

Histological type	Before USI	During USI	After USI	P
PTC	5.72%	28.77%	75.05%	<0.001
FTC	0.41%	0.60%	0.33%	<0.01
MTC	0.64%	0.49%	0.40%	NS

PTC, papillary thyroid cancer; FTC, follicular thyroid cancer; MTC, medullary thyroid cancer; USI, universal salt iodization.