title: Urinary retinol binding protein is a marker of the extent of interstitial kidney fibrosis.
abstract: Currently, a non-invasive method to estimate the degree of interstitial fibrosis (IF) in chronic kidney disease is not available in routine. The aim of our study was to evaluate the diagnostic performance of the measurement of urinary low molecular weight (LMW) protein concentrations as a method to determine the extent of IF. The urines specimen from 162 consecutive patients who underwent renal biopsy were used in the analysis. Numerical quantification software based on the colorimetric analysis of fibrous areas was used to assess the percentage IF. Total proteinuria, albuminuria, and the urinary levels of retinol binding protein (RBP), alpha1-microglobulin (α1MG), beta 2-microglobulin (β2MG), transferrin, and IgG immunoglobulins were measured. There was a significant correlation between the degree of IF and the RBP/creatinine (creat) ratio (R2: 0.11, p<0.0001). IF was associated to a lesser extent with urinary β2MG and α1MG; however, there was no association with total proteinuria or high molecular weight (HMW) proteinuria. The correlation between IF and RBP/creat remained significant after adjustment to the estimated glomerular filtration rate, age, body mass index, α1MG, and β2MG. The specificity of the test for diagnosing a fibrosis score of >25% of the parenchyma was 95% when using a threshold of 20 mg/g creat. In conclusion, RBP appears to be a quantitative and non-invasive marker for the independent prediction of the extent of kidney IF. Because methods for the measurement of urinary RBP are available in most clinical chemistry departments, RBP measurement is appealing for implementation in the routine care of patients with chronic kidney disease.
authors.affiliation: INSERM U775, Centre Universitaire des Saints Pères, Paris, France ; Service de Biochimie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pallet
authors.affiliation: Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chauvet
authors.affiliation: INSERM U775, Centre Universitaire des Saints Pères, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Chassé
authors.affiliation: INSERM U775, Centre Universitaire des Saints Pères, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Vincent
authors.affiliation: Departement d'informatique médicale, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Avillach
authors.affiliation: Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Charlene
authors.initials: C
authors.lastname: Levi
authors.affiliation: Unité d'Analyse d'image quantitative, Institut Pasteur, Paris, France.
authors.forename: Vannary
authors.initials: V
authors.lastname: Meas-Yedid
authors.affiliation: Unité d'Analyse d'image quantitative, Institut Pasteur, Paris, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Olivo-Marin
authors.affiliation: Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: Diane
authors.initials: D
authors.lastname: Nga-Matsogo
authors.affiliation: INSERM U775, Centre Universitaire des Saints Pères, Paris, France ; Service de Biochimie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Beaune
authors.affiliation: Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France ; Université Paris Descartes, Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Thervet
authors.affiliation: Service de Néphrologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Karras
mesh_terms: D015415:Biomarkers / Q000652:urine; D005260:Female; D005355:Fibrosis; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D051436:Renal Insufficiency, Chronic / Q000473:pathology / Q000503:physiopathology / Q000652:urine; D012177:Retinol-Binding Proteins / Q000737:chemistry / Q000652:urine*
chemical_list: D015415:Biomarkers; D012177:Retinol-Binding Proteins