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Table 2 Differences of perchlorate, iodine levels in urine between control and case group

From: The risk of perchlorate and iodine on the incidence of thyroid tumors and nodular goiter: a case-control study in southeastern China

Variables Pathological type Overall participants Controls Cases P-value a P-value b
Median 25th-75th percentiles Median 25th-75th percentiles Median 25th-75th percentiles
Perchlorate (μg/L) 11.27 6.89-18.49       
  Total cases    9.29 6.35-14.74 14.31 8.25-20.58 < 0.001
  NG    9.68 6.48-15.22 14.56 7.88-22.18 0.037 0.998
  PTMC    9.95 6.88-14.70 14.13 7.56-21.64 0.061
  PTC    8.73 5.75-13.39 14.27 8.67-19.16 0.002
Iodine (μg/L) 131.23 84.00-197.84       
  Total cases    131.59 82.13-183.25 131.23 84.46-214.92 0.153
  NG    122.67 66.63-171.41 130.19 79.60-205.02 0.165 0.836
  PTMC    138.58 100.43-181.96 148.34 95.15-213.52 0.589
  PTC    130.35 84.74-189.80 126.97 88.82-215.71 0.697
  1. Note: Data are presented as medians and 25–75 percentiles. Perchlorate and iodine were corrected by urinary specific gravity (USG). NG nodular goiter, PTMC papillary thyroid micro carcinoma, PTC papillary thyroid carcinoma, Total cases including NG, PTMC and PTC
  2. a P-value were derived from Wilcoxon signed-rank test between the case and control group
  3. b P-value was derived from the Kruskal-Wallis test between the three types of pathological