An automatic chemiluminescence immunoassay for a novel biomarker NT-IGFBP-4: analytical performance and clinical relevance in heart failure

Abstract Objectives Insulin-like growth factor binding protein-4 (IGFBP-4) fragments are reported as emerging biomarkers for cardiovascular disease (CVD) risk assessment. To ensure data reliability and improve clinical application, the first automatic chemiluminescent immunoassay (CLIA) for NT-IGFBP-4 was developed and its distribution across CVDs was evaluated in this study. Methods Fragment-specific monoclonal antibodies were used to develop immunoassay, followed by comprehensive analytical validation, including limit of blank (LoB), limit of detection (LoD), limit of quantification (LoQ), linearity, specificity, precision, sample type compatibility, and stability. Reference intervals for NT-IGFBP-4 were established in healthy individuals, with variations analyzed based on gender, age, body mass index (BMI), and renal function. Additionally, NT-IGFBP-4 distribution was explored in CVD patients. Results The newly developed chemiluminescence assay demonstrated high specificity for NT-IGFBP-4, with excellent sensitivity (LoQ=1.0 ng/mL), broad linearity (1.0–1,000.0 ng/mL), and strong precision (CV≤3.0 %). It showed no interference from common endogenous substances, maintained compatible with various sample types, and remained stable under different storage conditions. Reference intervals showed slight variations by gender and age, with levels being independent of BMI but influenced by renal function. NT-IGFBP-4 levels were significantly elevated in CVDs, especially in heart failure, correlating with NYHA classification and LVEF (%), with higher levels indicating worse cardiac function. Conclusions The new automatic NT-IGFBP-4 (CLIA) assay offers a highly specific, sensitive and precise method for quantifying IGFBP-4 fragments. Its validated performance and disease association findings would enhance its diagnostic and prognostic potential in CVD research, particularly in heart failure.