Kidney Week

Abstract: FR-PO1137

Comparison of GFR from Four- and Eight-Hour Iohexol Plasma Clearance in Patients with CKD

Session Information

• CKD: Screening, Diagnosis, Serum and Urine Biomarkers, and Scoring Indices
  November 07, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 2301 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Yadav, Ashok Kumar, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Ashok Kumar Yadav, PhD

• Kaur, Jaskiran, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Jaskiran Kaur, PhD

• Kaur, Rupinder, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Rupinder Kaur, MSW

• Agnihotri, Pratima, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Pratima Agnihotri, MSW

• Kohli, Harbir Singh, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Harbir Singh Kohli, MD

• Kumar, Vivek, Post Graduate Institute of Medical Education and Research, Chandigarh, CH, India

Vivek Kumar, MD, MBBS

• Jha, Vivekanand, The George Institute for Global Health India, New Delhi, DL, India

Vivekanand Jha, MD

Background

The optimal timing for measuring iohexol plasma clearance to determine glomerular filtration rate (GFR) in patients with advanced CKD remains unclear; however, extended sampling beyond 4 hours is generally recommended. The sampling time of exogenous filtration markers may significantly impact GFR measurement. We compared GFR measured by iohexol plasma measurements using 2, 3, and 4 hours and 2,3 and 8-hour samples.

Methods

Subjects with CKD from either sex, 18-70 years of age, were included. Multiple-sample plasma iohexol clearance was used to assess GFR. GFR was calculated at 4 hours (mGFR₄: 2,3, and 4 hours) and 8 hours (mGFR₈: 2,3, and 8 hours). We used mGFR₈ as a reference and compared it with mGFR₄. The agreement was evaluated with the concordance correlation coefficient (CCC), the total deviation index (TDI), and the coverage probability. CCC>0.9, TDI>10% and CP>90% reflect adequate accuracy.

Results

A total of 37 CKD subjects were enrolled. Median age of the study subjects was 50 years, and 62% of the participants were male. The mean mGFR₈ was lower than mGFR₄ (33±12 vs 37±17 mL/min/1.73m²). The mean absolute difference (mGFR₈-mGFR₄) was 3.63 mL/min/1.73m². In subjects with eGFR ≤30 ml/min/1.73 m², the mean absolute difference was less compared to subjects with eGFR>30 ml/min/1.73 m² (2.11 vs 5.42 ml/min/1.73 m²). Additionally, a moderate accuracy was observed between mGFR₄ and mGFR₈ with a CCC of 0.71, CP (76%) and TDI (20%).

Conclusion

mGFR measurements based on 4-hour sampling tend to overestimate GFR measured from a sampling duration of 8 hours and support the extended sampling in CKD subjects, specifically below GFR of <30 ml/min/1.73 m².

Funding

• Government Support – Non-U.S.

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.2025tgy48kbp