Kidney Week

Abstract: FR-PO1133

Association of Urine-to-Plasma Urea Ratio in Sickle Cell Disease with Glomerular Hyperfiltration

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

• Olaniran, Kabir O., The University of Texas Southwestern Medical Center, Dallas, Texas, United States

Kabir O. Olaniran, MD, MPH, FASN

• Bankir, Lise, INSERM, Paris, Île-de-France, France

Lise Bankir, PhD

• Moe, Orson W., The University of Texas Southwestern Medical Center, Dallas, Texas, United States

Orson W. Moe, MD

Background

Sickle cell disease (SCD) is associated with faster glomerular filtration rate (GFR) decline. But GFR decline in SCD is preceded by glomerular hyperfiltration (GH) and urine concentrating defects. Both GFR decline and urine concentrating capacity can be reliably assessed by the urine-to-plasma urea ratio (U/P_urea) in general population cohorts. However, U/P_urea and GH (creatinine estimated GFR [eGFR_creat]>120 mL/min) in SCD have not been investigated in detail.

Methods

We performed a 2-center cross-sectional study of adult Black race patients with chronic kidney disease (CKD) stages 1-5 excluding dialysis, between 2020-2025. SCD was confirmed by hemoglobin electrophoresis. U/P_urea was calculated from routine clinical care, same day random urine and plasma samples. Log-transformed U/P_urea (logU/P_urea) in SCD was compared to non-SCD in the entire cohort and in the GH sub-cohort (linear regression). In SCD only, we examined logU/P_urea GFR correlations (eGFR_creat and cystatin C [eGFR_cys]), trend tests across CKD stages, and determinants of logU/P_urea (stepwise linear regression). Multivariable analyses included demographics, vital signs, comorbidities and medications.

Results

We identified 2208 patients (128 SCD, 2080 non-SCD). The mean age was 64±17 years, 53% were female, the mean eGFR_creat was 40±30 mL/min, and 67 patients had GH. The median cohort U/P_urea was 11 (interquartile range 6-22). Before and after multivariable analysis, U/P_urea was significantly higher in SCD vs non-SCD (whole cohort 67.4% higher, p<0.01, and GH sub-cohort 44.8% higher, p=0.02). In SCD, eGFR_creat strongly correlated with logU/P_urea (r=0.73, p<0.01) but not with log urine-to-plasma non-urea solutes ratio (r=0.14, p=0.16). LogU/P_urea was moderately correlated with eGFR_cys in SCD (r=0.67, p<0.01). A significant negative trend from GH to CKD stages 1-5 in SCD was noted (eGFR_creatZ= -7.33, p<0.01 and eGFR_cys Z= -6.48, p<0.01). The most significant determinants of logU/P_urea in SCD were hemoglobin (58.4% higher per 5 g/dL increase, p<0.01) and GH (46.8% higher than eGFR_creat <120 mL/min, p<0.01), while age, body mass index, and albuminuria≧300 mg/g had p<0.05.

Conclusion

U/P_urea in SCD is significantly associated with GH and trends down with declining eGFR_creat. Longitudinal studies are needed to assess U/P_urea as a predictor of faster GFR decline and albuminuria in SCD.

Funding

• Other NIH Support

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.2025em8fbv89