Table 1 Change in thyroid characteristics between SHIP-0 (1997–2001) and SHIP-TREND (2008–2012)

Iodine, μg/l

123.0 (122.5; 123.5)

112.0 (111.5; 112.5)

<0.001

134.0 (133.2; 134.8)

126.0 (125.5; 126.5)

<0.001

108.0 (107.2; 108.8)

91.9 (91.4; 92.4)

<0.001

Iodine to creatinine ratio, μg/g

130.1 (129.8; 130.4)

113.7 (113.3; 114.0)

<0.001

116.2 (115.7; 116.8)

105.8 (105.4; 106.2)

<0.001

152.2 (151.4; 153.0)

128.0 (127.2; 128.8)

<0.001

Iodine < 100 μg/L, %

37.7 (36.0; 39.5)

43.9 (42.0; 45.7)

<0.001

30.5 (28.2; 32.9)

36.2 (33.9; 38.6)

0.001

45.6 (43.0; 48.3)

53.8 (51.0; 56.6)

<0.001

Thyroid volume, ml

18.41 (18.36; 18.46)

18.27 (18.24; 18.30)

<0.001

21.79 (21.71; 21.87)

20.39 (20.35; 20.44)

<0.001

15.31 (15.26; 15.36)

15.43 (15.40; 15.47)

<0.001

Goiter, %

35.1 (33.5; 36.7)

29.4 (27.8; 31.0)

<0.001

36.5 (34.2; 38.8)

26.6 (24.7; 28.7)

<0.001

33.7 (31.5; 36.0)

32.9 (30.4; 35.6)

0.676

Thyroid nodules, %

18.5 (17.3; 19.8)

30.5 (29.0; 32.1)

<0.001

14.8 (13.2; 16.7)

24.4 (22.5; 26.4)

<0.001

22.5 (20.7; 24.3)

38.4 (35.9; 41.0)

<0.001

Hypoechogenic thyroid pattern, %

5.4 (4.8; 6.2)

3.7 (3.1; 4.4)

0.001

1.8 (1.3; 2.4)

2.6 (1.9; 3.4)

0.113

9.5 (8.1; 11.0)

5.2 (4.1; 6.5)

<0.001

Increased anti-TPO antibodies, %

6.7 (5.8; 7.6)

5.2 (4.5; 6.0)

0.013

3.7 (2.9; 4.8)

3.7 (2.9; 4.7)

0.994

9.9 (8.5; 11.5)

7.1 (5.9; 8.6)

0.007

Positive anti-TPO antibodies, %

3.9 (3.2; 4.6)

2.9 (2.4; 3.5)

0.022

1.3 (0.9; 1.9)

1.4 (1.0; 2.1)

0.677

6.7 (5.6; 8.1)

4.7 (3.7; 6.0)

0.017

TSH, mIU/L

0.69 (0.68; 0.70)

1.19 (1.18; 1.20)

<0.001

0.68 (0.67; 0.69)

1.16 (1.15; 1.17)

<0.001

0.71 (0.70; 0.72)

1.24 (1.23; 1.25)

<0.001

Increased TSH, %

2.6 (2.1; 3.2)

2.9 (2.4; 3.6)

0.452

1.6 (1.1; 2.4)

2.4 (1.7; 3.3)

0.122

3.7 (2.9; 4.8)

3.6 (2.7; 4.8)

0.960

Decreased TSH, %

6.6 (5.8; 7.5)

6.4 (5.6; 7.3)

0.737

6.7 (5.6; 8.1)

6.4 (5.4; 7.6)

0.684

6.5 (5.4; 7.7)

6.4 (5.2; 7.8)

0.940