Table 3.
Comparison of Different Thyroid Parameters with 25(OH)D Quartiles and Seasons
| Thyroid Parameters | 25(OH)D Quartiles | F value | P value | |||
|---|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | |||
| Spring | ||||||
| TSH (mIU/mL) | 2.40 ± 1.41 | 2.27 ± 1.83 | 2.46 ± 2.2 | 2.37 ± 1.35 | 0.512 | 0.674 |
| FT3 (pmol/L) | 5.70 ± 0.64 | 5.63 ± 0.55 | 5.74 ± 0.95 | 5.73 ± 0.60 | 1.101 | 0.348 |
| FT4 (pmol/L) | 14.99 ± 2.44 | 14.45 ± 2.15 | 14.86 ±2.61 | 14.72 ± 2.3 | 2.269 | 0.079 |
| Summer | ||||||
| TSH (mIU/mL) | 2.32 ± 1.06 | 2.38 ± 1.92 | 2.41 ± 2.44 | 2.32 ± 1.20 | 0.079 | 0.971 |
| FT3 (pmol/L) | 5.51 ± 0.63 | 5.59 ± 0.68 | 5.51 ± 0.66 | 5.63 ± 0.55 | 1.529 | 0.206 |
| FT4 (pmol/L) | 14.56 ± 1.77 | 14.37 ± 1.89 | 13.95 ±1.53 | 14.37±1.80 | 3.261 | 0.021 |
| Autumn | ||||||
| TSH (mIU/mL) | 2.23 ± 1.69 | 2.28 ± 2.27 | 2.33 ± 1.06 | 2.25 ± 1.49 | 0.100 | 0.960 |
| FT3 (pmol/L) | 5.55 ± 0.79 | 5.62 ± 0.68 | 5.76 ± 0.73 | 5.71 ± 0.68 | 2.841 | 0.037 |
| FT4 (pmol/L) | 14.58 ± 2.12 | 14.58 ± 2.16 | 14.21 ±1.70 | 14.3 ± 2.09 | 1.429 | 0.233 |
| Winter | ||||||
| TSH (mIU/mL) | 2.46 ± 1.50 | 2.41 ± 1.33 | 2.18 ± 1.14 | 2.23 ± 1.13 | 1.574 | 0.195 |
| FT3 (pmol/L) | 5.55 ± 0.75 | 5.54 ± 0.69 | 5.62 ± 1.28 | 5.56 ± 0.73 | 0.222 | 0.881 |
| FT4 (pmol/L) | 14.99 ± 2.85 | 14.74 ± 2.16 | 14.84 ±2.84 | 14.62±2.34 | 0.492 | 0.688 |
Notes: 25(OH)D levels quartiles (Q1: 10.5–60.2 nmol/L, Q2: 60.3–76 nmol/L, Q3: 76.1–95.3 nmol/L, Q4: 95.3–280.8 nmol/L).
Abbreviations: 25(OH)D, serum 25-hydroxyvitamin D; FT3, free triiodothyronine; FT4, free thyroxine; TSH, thyroid stimulating hormone.