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Table 3 Comparison of 25(OH)D, free- and diplotype-corrected free 25(OH)D, and DBP and PTH concentrations among the GC haplotypes

From: Serum parathyroid hormone is related to genetic variation in vitamin D binding protein with respect to total, free, and bioavailable 25-hydroxyvitamin D in middle-aged Caucasians – a cross-sectional study

GC haplotype GC1S GC1F GC2 ANCOVA p-value
Dependent variable
S-25(OH)D (nmol/L) 57.1 (281) ± 1.04 50.6 (13) ± 4.9 52.7 (25) ± 3.53 0.231a
Free 25(OH)D (pmol/L) 12.5 (237) ± 0.30 10.1 (10) ± 1.46 12.6 (23) ± 0.97 0.280a
Diplotype corrected free 25(OH)D (pmol/L)e 14.2 (237) ± 0.35 6.30 (10) ± 1.70 22.8 (23) ± 1.12 <0.001 a
Bioavailable 25(OH)D (nmol/L) 4.92 (237) ± 0.12 3.98 (10) ± 0.59 5.01 (23) ± 0.39 0.261a
Diplotype corrected bioavailable 25(OH)D (nmol/L)e 5.61 (237) ± 0.14 2.47 (10) ± 0.68 9.15 (23) ± 0.45 <0.001 a
S-DBP (mg/L) 369 (240) ± 5.60 364 (10) ± 27.4 320 (23) ± 18.1 0.039 b
S-PTH (ng/L) 54.5 (283) ± 1.39 60.7 (13) ± 6.52 44.7 (25) ± 4.70 0.078cd
  1. Haplotype means were compared with ANCOVA ± SE. The values are adjusted estimates from ANCOVA. N in parenthesis
  2. Significant p-values are indicated in bold
  3. aAdjusted for age, S-PTH, vitamin D intake, sunlight exposure and sex
  4. bAdjusted for BMI and sex
  5. cS-25(OH)D, Ca intake
  6. da linear trend, p = 0.044
  7. GC haplotype was used as a fixed factor
  8. eHaplotype-corrected free and bioavailable 25(OH)D values were calculated by placing a haplotype-specific binding coefficient into the free and bioavailable formulae