Table 5.
Growth and Bone Parameters in Sex‐Specific Tertiles of CXM in 24‐Month‐Old Infants According to Vitamin D Intervention Group
| CXM | Lowest (first tertile) | Intermediate (second tertile) | Highest (third tertile) | p Value |
|---|---|---|---|---|
| Mean (95% CI) | ||||
| Group‐10 | ||||
| n | 39 | 44 | 33 | |
| Length (SDS) | −0.59 (−0.92, −0.26) | −0.23 (−0.58, 0.13) | −0.19 (−0.54, 0.16) | 0.19 |
| Length (cm) | 86.7 (85.7, 87.7) | 87.9 (86.8, 89.0) | 87.7 (86.6, 88.8) | 0.23 |
| Growth rate in length (SD unit) | −0.37 (−0.66, −0.07) | −0.27 (−0.54, 0.00) | 0.17 (−0.13, 0.46) | 0.028 a |
| Length velocity (cm/yr) | 11.9 (11.4, 12.4) | 12.1 (11.6, 12.6) | 12.7 (12.1, 13.2) | 0.086 |
| Tibial length (mm) | 165 (162, 168) | 168 (165, 170) | 169 (166, 172) | 0.11 |
| Tibial length velocity (mm/yr) | 28.1 (25.5, 30.8) | 30.1 (27.6, 32.6) | 31.6 (28.5, 34.6) | 0.22 |
| BMC (mg/mm) | 52.7 (50.3, 55.2) | 55.2 (52.7, 57.7) | 54.2 (51.5, 57.0) | 0.35 |
| ΔBMC (mg/mm/yr) | 17.8 (15.6, 20.0) | 19.4 (17.0, 21.9) | 19.5 (17.4, 21.7) | 0.50 |
| vBMD (mg/cm3) | 378 (357, 400) | 374 (348, 400) | 357 (230, 385) | 0.49 |
| ΔvBMD (mg/cm3/yr) | 83.8 (52.7, 115.0) | 66.1 (42.1, 90.2) | 65.3 (29.4, 101.2) | 0.61 |
| CSA (mm2)b | 145 (136, 154) | 152 (144, 161) | 155 (145, 165) | 0.35 |
| ΔCSA (mm2/yr) | 16.8 (6.0, 27.7) | 31.6 (19.7, 43.5) | 33.1 (18.1, 48.1) | 0.13 |
| PMI (mm4)b | 3561 (3067, 4054) | 3943 (3482, 4403) | 4102 (3567, 4638) | 0.32 |
| ΔPMI (mm4/yr) | 660 (166, 1154) | 1355 (681, 2029) | 1591 (849, 2332) | 0.11 |
| PsC (mm) b | 42.5 (41.2, 43.8) | 43.5 (42.3, 44.7) | 43.8 (42.4, 45.2) | 0.37 |
| ΔPsC (mm/yr) | 2.78 (1.11, 4.46) | 4.94 (3.30, 6.59) | 4.96 (2.73, 7.18) | 0.15 |
| PTH (pg/mL) | 18.4 (14.8, 22.0) | 20.6 (17.4, 23.9) | 18.0 (15.8, 20.2) | 0.31 |
| iCa (mmol/L) | 1.31 (1.30, 1.32) | 1.31 (1.29, 1.32) | 1.31 (1.30, 1.32) | 0.83 |
| 25(OH)D (nmol/L) | 86.5 (80.4, 92.7) | 87.5 (80.7, 94.3) | 81.3 (76.6, 86.0) | 0.34 |
| Group‐30 | ||||
| n | 52 | 45 | 57 | |
| Length (SDS) | −0.39 (−0.65, −0.12) | −0.49 (−0.83, −0.15) | −0.22 (−0.53, 0.09) | 0.43 |
| Length (cm5) | 87.2 (86.4, 88.0) | 86.9 (85.8, 87.9) | 87.7 (86.8, 88.6) | 0.39 |
| Growth rate in length (SD unit) | 0.05 (−0.24, 0.34) | 0.05 (−0.23, 0.32) | 0.10 (−0.18, 0.39) | 0.95 |
| Length velocity (cm/yr) | 12.5 (12.0, 12.9) | 12.5 (12.1, 13.0) | 12.6 (12.1, 13.1) | 0.94 |
| Tibial length (mm) | 166 (163, 168) | 165 (163, 168) | 166 (164, 169) | 0.87 |
| Tibial length velocity (mm/yr) | 29.3 (27.3, 31.4) | 29.0 (26.6, 31.4) | 29.7 (27.4, 32.0) | 0.90 |
| BMC (mg/mm) | 55.1 (52.7, 57.4) | 54.2 (51.6, 56.8) | 55.2 (53.0, 57.5) | 0.82 |
| ΔBMC (mg/mm/yr) | 19.1 (16.1, 22.0) | 18.5 (16.3, 20.7) | 19.6 (17.4, 21.7) | 0.82 |
| vBMD (mg/cm3) | 381 (359, 402) | 374 (353, 395) | 385 (366, 405) | 0.74 |
| ΔvBMD (mg/cm3/yr) | 84.3 (58.6, 110.0) | 62.5 (31.8, 93.3) | 91.3 (68.1, 114.5) | 0.29 |
| CSA (mm2)b | 149 (142, 155) | 148 (141, 154) | 145 (139, 151) | 0.76 |
| ΔCSA (mm2/yr) | 23.3 (12.6, 34.0) | 28.7 (17.2, 40.1) | 21.2 (13.9, 28.4) | 0.55 |
| PMI (mm4)b | 3731 (3411, 4050) | 3642 (3299, 3986) | 3542 (3237, 3847) | 0.70 |
| ΔPMI (mm4/yr) | 922 (363, 1480) | 1169 (616, 1722) | 915 (573, 1258) | 0.71 |
| PsC (mm) b | 43.0 (42.1, 43.9) | 42.9 (42.0, 43.9) | 42.6 (41.8, 43.5) | 0.80 |
| ΔPsC (mm/yr) | 3.79 (2.23, 5.34) | 4.63 (2.92, 6.33) | 3.34 (2.26, 4.43) | 0.45 |
| PTH (pg/mL) | 15.9 (13.9, 17.9) | 17.6 (15.1, 20.0) | 16.7 (14.3, 19.0) | 0.69 |
| iCa (mmol/L) | 1.31 (1.30, 1.32) | 1.31 (1.30, 1.33) | 1.31 (1.31, 1.32) | 0.99 |
| 25(OH)D (nmol/L) | 114.3 (106.4, 122.2) | 113.1 (106.1, 120.1) | 121.6 (115.0, 128.1) | 0.19 |
CXM = collagen X biomarker; CI = confidence interval; group‐10 = vitamin D intervention group receiving 10 μg/d; group‐30 = vitamin D intervention group receiving 30 μg/d; SDS = standard deviation score; BMC = total bone mineral content; vBMD = total volumetric bone mineral density; CSA = total cross‐sectional area; PMI = total polar moment of inertia; PsC = periosteal circumference; Δ = change between measurements at 12 and 24 months; PTH = parathyroid hormone; iCa = ionized calcium; 25(OH)D = 25‐hydroxy‐vitamin D.
Statistical significance between tertiles analyzed using ANOVA and ANCOVA.
CXM tertiles among girls: lowest, 15.65–32.03 ng/mL; intermediate, 32.19–40.88 ng/mL; highest, 41.27–93.51 ng/mL; and among boys: lowest, 17.09–32.15 ng/mL; intermediate, 32.50–39.87 ng/mL; highest, 39.99–72.99 ng/mL.
Significance between first and third tertile (mean difference [95% CI] –0.53 [−1.04, −0.03], p = 0.034).
Adjusted for tibial length (mm) at 24 months.