Table 3.

Changes in serum TSH levels at the 2.5th, 50th, and 97.5th percentiles between 2009 and 2015 among adults in China. The changes in quantiles of TSH were adjusted for BMI, family history of thyroid disorders, education level, and smoking status.

TSH percentile	TSH levels (95% CI)		Adjusted change in quantiles of TSH (95% CI)	P-value
	2009–2010	2015–2017
Overall population
n	14 925	12 553
2.5th	0.66 (0.61 to 0.70)	0.73 (0.69 to 0.79)	0.15 (0.01 to 0.30)	0.04
50th	2.36 (2.28 to 2.48)	2.43 (2.34 to 2.54)	−0.003 (−0.14 to 0.14)	0.96
97.5th	7.88 (7.53 to 8.25)	7.70 (7.21 to 8.61)	−0.10 (−1.47 to 1.26)	0.88
Reference population
n	11 489	9879
2.5th	0.78 (0.75 to 0.82)	0.80 (0.76 to 0.86)	0.13 (0.01 to 0.26)	0.04
50th	2.32 (2.25 to 2.44)	2.42 (2.33 to 2.53)	−0.003 (−0.15 to 0.14)	0.96
97.5th	6.71 (6.49 to 6.97)	7.21 (6.15 to 8.45)	0.20 (−0.87 to 1.26)	0.72