Nickan Research Institute Journal of Renal Injury Prevention 2345-2781 15 4 2026 12 01 Comparison of inferior vena cava indices as markers of volume status in hemodialysis patients and healthy individuals; a case–control study e38775 e38775 10.34172/jrip.38775 EN Sepideh Hajian https://orcid.org/0000-0002-3368-0036 Majid Hajikarimi https://orcid.org/0000-0002-1543-5870 Pourya Fathollahzadeh https://orcid.org/0000-0003-0561-9921 Sadaf Rahgodaz https://orcid.org/0009-0006-7840-4699 Arian Ghannadi Karimi https://orcid.org/0000-0002-5241-4905 Niki Sadat Mosallaei https://orcid.org/0009-0009-8828-8996 Mohammad Taghipour https://orcid.org/0009-0000-8468-7396 Journal Article 10.34172/jrip.38775 2026 05 15 2026 07 02 Introduction: Volume status assessment is critical in hemodialysis (HD) patients because fluid overload is closely related to cardiovascular complications and mortality. Inferior vena cava (IVC) diameter and collapsibility measured by ultrasound provide simple noninvasive estimates of intravascular volume, but comparative data versus healthy individuals are limited. Objectives: This study therefore compares IVC indices between HD patients and healthy controls to evaluate their usefulness as markers of volume status in clinical practice. Materials and Methods: This case–control study included 53 maintenance HD patients and 48 age- and sex-matched healthy controls recruited at Qazvin Velayat hospital between December 2024 and September 2025. Demographic and anthropometric data were recorded, and all participants underwent multi-frequency bioimpedance analysis and standardized ultrasonographic assessment of IVC diameters (maximum and minimum) and collapsibility index (categorical < 50% versus > 50%). Statistical comparisons between HD and control groups, as well as regression analyses of the association between HD status and IVC indices, were performed using SPSS version 27. Results: Among the evaluated markers of volume status, HD status was associated with larger IVC diameters and reduced collapsibility compared with healthy individuals. In linear regression models, HD was associated with an increase of 4.02 mm in maximum IVC diameter (95% confidence interval [CI]: 2.76–5.27) and 4.29 mm in minimum diameter (95% CI: 2.86–5.71). In addition, in logistic regression analysis, HD patients had higher odds of having a collapsibility index below 50%, with an odds ratio of 3.07 (95% CI: 1.24–7.62), indicating a substantially greater likelihood of reduced vena cava collapsibility in this group. Conclusion: These results indicate that HD patients have a pattern of larger IVC diameters and reduced collapsibility compared with healthy individuals, supporting IVC ultrasound indices as practical noninvasive markers of volume overload in this population.