Clinical Significance of IVC Collapsibility Index and BNP for Volume Assessment in Nephrotic Syndrome: A Case–Control Study.

Background: Determining effective circulating volume in nephrotic syndrome is challenging because peripheral edema does not reliably reflect intravascular status. Clinical assessment is often imprecise, and invasive monitoring is impractical for routine care. Inferior vena cava collapsibility index (IVC-CI) and brain natriuretic peptide (BNP) are noninvasive bedside markers that may improve volume assessment. Objective: To evaluate the clinical utility of IVC-CI and BNP for intravascular volume assessment in nephrotic syndrome and to compare their performance across IVC-CI–defined volume categories. Methods: In this case–control study, 70 adults with nephrotic syndrome and 35 healthy controls were enrolled (October 2024–October 2025). Nephrotic patients were stratified as non-hypervolemic (IVC-CI 20–50%; n=52) or hypervolemic(IVC-CI