title: Urinary Angiotensinogen and Renin Excretion are Associated with Chronic Kidney Disease.
abstract: OBJECTIVE
  Several studies sought to identify new biomarkers for chronic kidney disease (CKD). As the renal renin-angiotensin system is activated in CKD, urinary angiotensinogen or renin excretion may be suitable candidates. We tested whether urinary angiotensinogen or renin excretion is elevated in CKD and whether these parameters are associated with estimated glomerular filtration rate (eGFR). We further tested whether urinary angiotensinogen or renin excretion may convey additional information beyond that provided by albuminuria.
  
  
  METHODS
  We measured urinary and plasma angiotensinogen, renin, albumin and creatinine in 177 CKD patients from the Greifswald Approach to Individualized Medicine project and in 283 healthy controls from the Study of Health in Pomerania. The urinary excretion of specific proteins is given as protein-to-creatinine ratio. Receiver operating characteristic (ROC) curves, spearman correlation coefficients and linear regression models were calculated.
  
  
  RESULTS
  Urinary angiotensinogen [2,511 (196-31,909) vs. 18.6 (8.3-44.0) pmol/g, *P<0.01] and renin excretion [0.311 (0.135-1.155) vs. 0.069 (0.045-0.148) pmol/g, *P<0.01] were significantly higher in CKD patients than in healthy controls. The area under the ROC curve was significantly larger when urinary angiotensinogen, renin and albumin excretion were combined than with urinary albumin excretion alone. Urinary angiotensinogen (ß-coefficient -2.405, standard error 0.117, P<0.01) and renin excretion (ß-coefficient -0.793, standard error 0.061, P<0.01) were inversely associated with eGFR. Adjustment for albuminuria, age, sex, systolic blood pressure and body mass index did not significantly affect the results.
  
  
  CONCLUSIONS
  Urinary angiotensinogen and renin excretion are elevated in CKD patients. Both parameters are negatively associated with eGFR and these associations are independent of urinary albumin excretion. In CKD patients urinary angiotensinogen and renin excretion may convey additional information beyond that provided by albuminuria.
authors.affiliation: Institute of Physiology, Greifswald, Germany.
authors.forename: Annett
authors.initials: A
authors.lastname: Juretzko
authors.affiliation: Institute of Physiology, Greifswald, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Steinbach
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, Greifswald, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Hannemann
authors.affiliation: Institute of Anatomy and Cell Biology, Greifswald, Germany.
authors.forename: Karlhans
authors.initials: K
authors.lastname: Endlich
authors.affiliation: Institute of Anatomy and Cell Biology, Greifswald, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Endlich
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, Greifswald, Germany.
authors.forename: Nele
authors.initials: N
authors.lastname: Friedrich
authors.affiliation: Institute of Medical Biochemistry and Molecular Biology, Greifswald, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Lendeckel
authors.affiliation: Clinic for Internal Medicine A, University of Greifswald, Greifswald, Germany.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Stracke
authors.affiliation: Institute of Physiology, Greifswald, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Rettig
mesh_terms: D000368:Aged; D000419:Albuminuria; D000808:Angiotensinogen / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D051436:Renal Insufficiency, Chronic / Q000652:urine*; D012083:Renin / Q000652:urine*
chemical_list: D015415:Biomarkers; D000808:Angiotensinogen; D012083:Renin
keywords: Angiotensinogen; Biomarkers; Chronic kidney disease; Epidemiology; Renin-angiotensin system