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Published on: January 28, 2013
Urinary Retinol-Binding Protein: Relationship to Renal Function and Cardiovascular Risk Factors in Chronic Kidney
Maria Alice Muniz Domingos1, Silvia Regina Moreira2, Luz Gomez3
1Nephrology Division, Department of Clinical Medicine, Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
Insights
Urinary retinol-binding protein (RBP) is a significant biomarker for general chronic kidney disease (CKD) and its progression. This finding expands RBP
Area of Science:
- Nephrology
- Biomarker Discovery
- Clinical Chemistry
Background:
- Urinary retinol-binding protein (RBP) is a recognized biomarker for CKD in specific conditions like proximal tubular diseases, glomerulopathies, and post-transplantation.
- Its role in general CKD progression and renal damage remains less understood.
Purpose of the Study:
- To investigate the association between urinary RBP and renal function, as well as cardiovascular risk factors, in patients with stages 3 and 4 CKD.
- To determine if urinary RBP can serve as a biomarker for CKD progression in a broader patient population.
Main Methods:
- Analysis of baseline data from the Progredir Study, a CKD cohort in Sao Paulo, Brazil, with 454 participants.
- Univariate and adjusted regression analyses to assess the relationship between urinary RBP, estimated glomerular filtration rate (eGFR), and cardiovascular risk factors.
- Evaluation of RBP's ability to improve diagnostic accuracy for reduced eGFR.
Main Results:
- Urinary RBP showed an inverse relationship with eGFR and several cardiovascular risk factors in univariate analysis.
- After adjustments, eGFR, albuminuria, systolic blood pressure, anemia, acidosis, and left atrium diameter remained significantly associated with urinary RBP.
- The inverse association between eGFR and urinary RBP persisted across all albuminuria strata and improved the diagnostic accuracy for eGFR < 35 ml/min/1.73m².
Conclusions:
- Urinary RBP is significantly associated with renal function in general CKD, extending its utility beyond specific kidney conditions.
- Urinary RBP holds potential as a predictive marker for CKD progression and warrants further investigation.
Abstract:
The role of urinary retinol-binding protein (RBP) as a biomarker of CKD in proximal tubular diseases, glomerulopathies and in transplantation is well established. However, whether urinary RBP is also a biomarker of renal damage and CKD progression in general CKD is not known. In this study, we evaluated the association of urinary RBP with renal function and cardiovascular risk factors in the baseline data of the Progredir Study, a CKD cohort in Sao Paulo, Brazil, comprising 454 participants with stages 3 and 4 CKD. In univariate analysis, urinary RBP was inversely related to estimated glomerular filtration rate (CKD-EPI eGFR) and several cardiovascular risk factors. After adjustments, however, only CKD-EPI eGFR, albuminuria, systolic blood pressure, anemia, acidosis, and left atrium diameter remained significantly related to urinary RBP. The inverse relationship of eGFR to urinary RBP (β-0.02 ± 95CI -0.02; -0.01, p<0.0001 for adjusted model) remained in all strata of albuminuria, even after adjustments: in normoalbuminuria (β-0.008 ± 95CI (-0.02; -0.001, p = 0.03), in microalbuminuria (β-0.02 ± 95CI (-0.03; -0.02, p<0,0001) and in macroalbuminuria (β-0.02 ± 95CI (-0.03; -0.01, p<0,0001). Lastly, urinary RBP was able to significantly increase the accuracy of a logistic regression model (adjusted for sex, age, SBP, diabetes and albuminuria) in diagnosing eGFR<35 ml/min/1.73m2 (AUC 0,77, 95%CI 0,72-0,81 versus AUC 0,71, 95%CI 0,65-0,75, respectively; p = 0,05). Our results suggest that urinary RBP is significantly associated to renal function in CKD in general, a finding that expands the interest in this biomarker beyond the context of proximal tubulopathies, glomerulopathies or transplantation. Urinary RBP should be further explored as a predictive marker of CKD progression.
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