title: The origin and the clinical significance of urinary angiotensinogen in proteinuric IgA nephropathy patients.
abstract: BACKGROUND
  Urinary angiotensinogen (AGT) was reported as a marker of renal injury in chronic kidney disease patients. However, the main source of urinary AGT is unknown in proteinuric patients because the disrupted filtration barrier might cause AGT filtration. We investigated the origin and the clinical importance of urinary AGT in proteinuric IgA nephropathy (IgAN) patients.
  
  
  METHODS
  In patients with biopsy-proven IgAN, urinary and plasma AGT was measured using a sandwich ELISA and compared with intrarenal AGT expression. The patients were followed up for 3 years.
  
  
  RESULTS
  Natural logarithm of the urinary AGT/creatinine (ln (urinary AGT/Cr)) was positively correlated with intrarenal expression of AGT (ln (urinary AGT/Cr) versus AGT/β-actin, r = 0.620, P < 0.0001; ln (urinary AGT/Cr) versus AGT density, r = 0.452, P = 0.007). Ln (urinary AGT/Cr) showed a positive correlation with urinary protein/creatinine ratio (PCR) but a negative correlation with estimated glomerular filtration rate (eGFR). Regression analyses showed that ln (urinary AGT/Cr) was a significant determinant of urinary PCR and eGFR 3 years after biopsy.
  
  
  CONCLUSIONS
  Urinary AGT reflects intrarenal AGT expression and correlates with the extent of proteinuria and renal function. Our study indicates the intrarenal compartment as the main source of urinary AGT, suggesting its clinical implication as an important biomarker in proteinuric IgAN patients.
authors.affiliation: Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hye Ryoun
authors.initials: HR
authors.lastname: Jang
authors.forename: Soo Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Yu-Ji
authors.initials: YJ
authors.lastname: Lee
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Wooseong
authors.initials: W
authors.lastname: Huh
authors.forename: Dae Joong
authors.initials: DJ
authors.lastname: Kim
authors.forename: Ha Young
authors.initials: HY
authors.lastname: Oh
authors.forename: Yoon-Goo
authors.initials: YG
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000808:Angiotensinogen / Q000652:urine*; D005260:Female; D005500:Follow-Up Studies; D005922:Glomerulonephritis, IGA / Q000150:complications / Q000652:urine*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000150:complications / Q000652:urine*; D055815:Young Adult
chemical_list: D000808:Angiotensinogen