Kidney Week

Abstract: TH-PO0722

Defining the Relationship Between Urine Albumin-to-Creatinine Ratio and Urine Protein-to-Creatinine Ratio in the Nephrotic Syndrome Study Network (NEPTUNE)

Session Information

• Glomerular Innovations: Artificial Intelligence, Multiomics, and Biomarkers
  November 06, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Wyatt, Nicole Elizabeth, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States

Nicole Elizabeth Wyatt, DO

• Helmuth, Margaret, University of Michigan, Ann Arbor, Michigan, United States

Margaret Helmuth, MA

• Derebail, Vimal K., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States

Vimal K. Derebail, MD, MPH, FASN

• Mariani, Laura H., University of Michigan, Ann Arbor, Michigan, United States

Laura H. Mariani, MD, MS, FASN

• Smith, Abigail R., Northwestern University, Evanston, Illinois, United States

Abigail R. Smith, PhD

Group or Team Name

• Nephrotic Syndrome Study Network (NEPTUNE).

Background

Use of albumin:creatinine ratio (UACR) or protein:creatinine ratio (UPCR) to assess glomerular disease activity varies widely by practice. The PARASOL initiative assessed proteinuria and eGFR as surrogate endpoints in focal segmental glomerulosclerosis (FSGS). Challenges arose due to differences in proteinuria reporting across registries and lack of accepted conversion. No large, multicenter studies have investigated the relationship between UACR and UPCR in glomerular diseases.

Methods

We conducted a cross-sectional analysis of patients with biopsy proven FSGS, minimal change disease (MCD), and membranous nephropathy (MN) in NEPTUNE. We included samples with same day UACR and UPCR from both spot and timed urine collections. Linear regression models were used to assess the relationship between UACR and UPCR.

Results

There were 3540 observations across 595 patients with FSGS (n=234), MCD (n=223), and MN (n=138) with median (IQR) age of 31 years (13, 53) and median (IQR) eGFR at baseline of 84 ml/min/1.73m² (58, 102). A strong correlation between UACR and UPCR was observed across the cohort, with a regression slope of 0.8. Regression slopes within each disease ranged from 0.75-0.85. No differences in slope were detected at lower proteinuria levels (<0.5 g/g, regression slope range 0.82-0.83, Figure). This relationship was consistent when adjusted for age, sex, race, ethnicity and eGFR.

Conclusion

UACR and UPCR are highly correlated in FSGS, MCD, and MN regardless of disease and severity of proteinuria. Our data support interchangeable use of UACR or UPCR with a reliable conversion factor. These findings will facilitate future validation analysis in PARASOL as well as other multi-institutional projects, improving generalizability and increasing power of proteinuria-based endpoint validation efforts.

Funding

• NIDDK Support

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.2025jj2a0ny8