<p>Data.</p>

Based on the measured levels, vitamin D status was categorized as deficient (< 20 ng/mL), insufficient (≥20, < 30 ng/mL), or sufficient (≥ 30 ng/mL).</p> <p>Results</p><p>The intra-assay coefficients of variation (CV) were 3.18%, 2.09%, and 1.86% at three concentration levels (5, 25, and 100 ng/mL), while intermediate precision CVs were 4.34%, 3.64%, and 3.17%, respectively. Accuracy testing showed bias of 4.20% and 3.26% at 20 and 50 ng/mL.

The assay demonstrated excellent linearity (R² = 0.998) across the range of 4.0-150.0 ng/mL. No significant interference was observed from hemoglobin (100 mg/dL), bilirubin (40 mg/dL), triglycerides (400 mg/dL), or rheumatoid factor (600 IU/mL). In method comparison with LC-MS/MS, the Innodx vitamin D assay demonstrated strong concordance with a Pearson correlation coefficient of r = 0.970.

When compared with the Roche vitamin D assay, the Innodx showed better correlation with LC-MS/MS. Among 495 women, the mean 25(OH)D concentration was 20.50 ± 7.88 ng/mL, with 88.9% (95% CI: 86.1%, 91.7%) having vitamin D deficiency or insufficiency. Women aged ≤ 25 years showed significantly lower levels (18.38 ± 6.26 ng/mL) compared to older groups (31–35 years: 23.31 ± 8.97 ng/mL; > 35 years: 23.72 ± 8.56 ng/mL) (<i>P</i> < 0.05).</p> <p>Conclusion</p><p>The Innodx vitamin D chemiluminescence assay demonstrated satisfactory analytical performance for clinical use.

Our findings reveal a high prevalence of vitamin D deficiency among reproductive-age women in southeastern China, particularly in younger age groups, highlighting the need for public health interventions.</p></div>