Abstract
BACKGROUND: 25-Hydroxy vitamin D [25(OH)D] is the circulating form of vitamin D. Its deficiency is a major global health concern, affecting over one billion people. Beyond its role in bone health, low vitamin D levels have been implicated in a wide range of chronic and inflammatory diseases, including diabetes, chronic kidney disease, and cancer. While immunoassays are widely used in routine testing, liquid chromatography-tandem mass spectrometry (LC-MS/MS) remains the reference method for its superior accuracy. This study aimed to evaluate the analytical performance of the Autobio 25(OH)D chemiluminescence assay (Autobio Diagnostics, Zhengzhou, China) compared with LC-MS/MS (Chromsystems Instruments & Chemicals GmbH, Gräfelfing, Germany) and the Siemens chemiluminescent microparticle immunoassay (Siemens HealthCare, Erlangen, Germany). Additionally, the influence of age and sex on 25(OH)D concentrations was examined to explore potential demographic and pathophysiological variations. METHODS: 200 residual serum samples were analyzed to compare all three methods. Precision and linearity were verified. Statistical analysis was performed. RESULTS: The Autobio assay showed good correlation with LC-MS/MS (R(2) = 0.953; p < 0.001), with acceptable bias and precision (CV < 10%) and confirmed linearity. Age- and sex-related differences were observed, indicating demographic influences on vitamin D status. CONCLUSIONS: Accurate and accessible laboratory testing for 25(OH)D is therefore essential for both disease prevention and clinical management. The Autobio 25(OH)D assay demonstrated strong correlation with LC-MS/MS and high analytical reliability. Its good performance makes it a valuable tool for routine assessment of 25(OH)D and for supporting the early detection or monitoring of hypovitaminosis D in clinical practice.