Table 2. Associations between selenium status and thyroid function tests.
| TFTs | SePP | Se | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linear regression | Quartiles | Linear regression | Quartiles | ||||||
| Normal value | B(SE) | P | Q1 Mean(SE) | Q4 Mean(SE) | B(SE) | P | Q1 Mean(SE) | Q4 Mean(SE) | |
| TSH, mU/L | 0.4–4.3 | <0.01(0.07) | 0.95 | 1.24(0.10) | 1.14(0.10) | <0.01(0.03) | 0.98 | 1.23(0.10) | 1.30(0.10) |
| FT4, pmol/L | 11–25 | 0.11(0.21) | 0.60 | 16.4(0.33) | 16.7(0.32) | 0.01(0.01) | 0.11 | 16.2(0.32) | 16.7(0.32) |
| T4, nmol/L | 58–128 | 1.73(1.07) | 0.11 | 79.1(1.68) | 81.3(1.64) | 0.03(0.05) | 0.45 | 80.1(1.66) | 79.2(1.65) |
| T3, nmol/L | 1.43–2.51 | <0.01(0.02) | 0.92 | 1.45(0.03) | 1.41(0.02) | <0.01(0.01) | 0.80 | 1.40(0.02) | 1.41(0.02) |
| rT3, nmol/L | 0.14–0.34 | 0.01(0.01) | 0.22 | 0.32(0.01) | 0.33(0.01) | <0.01(0.01) | 0.96 | 0.33(0.01) | 0.32(0.01) |
| T3/T4 x100 | 1.42–3.05 | -0.05(0.03) | 0.11 | 1.95(0.05) | 1.78(0.05) | <0.01(0.01) | 0.95 | 1.82(0.05) | 1.89(0.05) |
| T3/rT3 | 3.12–13.03 | -0.15(0.11) | 0.30 | 5.01(0.16) | 4.56(0.16) | <0.01(0.01) | 0.95 | 4.69(0.16) | 4.72(0.16) |
| rT3/T4x100 | 0.15–0.44 | <0.01(0.01) | 0.97 | 0.41(0.01) | 0.41(0.01) | <0.01(0.01) | 0.84 | 0.42(0.01) | 0.42(0.01) |
The results (B(SE) and corresponding P-values) of the linear regression analyses of SePP and Se levels versus various TFTs are shown. In addition, mean values for the lowest and highest Se and SePP quartiles are presented to provide extra insight into the actual effects. Abbreviations: B, Beta; FT4, free thyroxine; rT3, reverse triiodothyronine; Se, Selenium; (SE), standard error; SePP, selenoprotein P; TFTs, thyroid function tests; TSH, thyroid stimulating hormone; T3, triiodothyronine; T4, thyroxine; Q1, first quartile; Q4, fourth quartile