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Table 1 Participants in the two groups differing by thyroid function. The euthyroid participants had TSH and T4 within the population-based reference range while the participants with subclinical (mild) hypothyroidism had elevated TSH and T4 within the reference range in two separate blood samples prior to inclusion. Twelve monthly blood samplings were done in all participants

From: Interpretation of TSH and T4 for diagnosing minor alterations in thyroid function: a comparative analysis of two separate longitudinal cohorts

 

Euthyroid

Mildly hypothyroidb

P-value

Number of participants

15

20

 

Number of samples

180

240

 

Age, range (mean;SD), yearsa

26–53 (39;10)

27–78 (57;12)

< 0.001

Sex, men, n

15

2

< 0.001

Weight, mean (SD), kga

81 (11)

77 (14)

0.32

Current smoker, n

11

4

0.02

TSH, mean (SD), CV%

1.27 (0.56), 44.0

7.19 (3.03), 42.1

< 0.001

 0.3–4.5 mIU/L, n (%)

180 (100)

31 (12.9)

 

 > 4.5 mIU/L, n (%)

0 (0.0)

209 (87.1)

 

TT4, mean (SD), CV%

106.4 (20.8), 19.6

85.5 (16.2), 18.9

< 0.001

 60–140 nmol/L, n (%)

179 (99.4)

233 (97.1)

NS

 < 60 nmol/L, n (%)

1 (0.6)

7 (2.9)

 

fT4 index, mean (SD), CV%

102.4 (20.9), 20.4

  

 70–140 nmol/L, n (%)

176 (97.8)

  

 < 70 nmol/L, n (%)

4 (2.2)

  

fT4, mean (SD), CV%

 

13.0 (2.4), 18.6

 

 12 + pmol/L, n (%)

 

188 (78.3)

 

 < 12 pmol/l, n (%)

 

52 (21.7)

 
  1. TSH: Thyrotropin, TT4: Total thyroxine, fT4: Free thyroxine
  2. a SD Standard deviation
  3. b One participant had subsequent measures of TSH and T4 within the reference range. Without this participant mean TSH was 7.39 mIU/L while mean T4 was unaltered