title: Urinary markers of intrarenal renin-angiotensin system activity in vivo.
abstract: Recent interest focuses on urinary renin and angiotensinogen as markers of renal renin-angiotensin system activity. Before concluding that these components are independent markers, we need to exclude that their presence in urine, like that of albumin (a protein of comparable size), is due to (disturbed) glomerular filtration. This review critically discusses their filtration, reabsorption and local release. Given the close correlation between urinary angiotensinogen and albumin in human studies, it concludes that, in humans, urinary angiotensinogen is a filtration barrier damage marker with the same predictive power as urinary albumin. In contrast, in animals, tubular angiotensinogen release may occur, although tubulus-specific knockout studies do not support a functional role for such angiotensinogen. Urinary renin levels, relative to albumin, are >200-fold higher and unrelated to albumin. This may reflect release of renin from the urinary tract, but could also be attributed to activation of filtered, plasma-derived prorenin and/or incomplete tubular reabsorption.
authors.affiliation: Division of Pharmacology and Vascular Medicine, Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Lodi C W
authors.initials: LC
authors.lastname: Roksnoer
authors.forename: Koen
authors.initials: K
authors.lastname: Verdonk
authors.forename: Anton H
authors.initials: AH
authors.lastname: van den Meiracker
authors.forename: Ewout J
authors.initials: EJ
authors.lastname: Hoorn
authors.forename: Robert
authors.initials: R
authors.lastname: Zietse
authors.forename: A H Jan
authors.initials: AH
authors.lastname: Danser
mesh_terms: D000808:Angiotensinogen / Q000652:urine*; D000818:Animals; D015415:Biomarkers / Q000652:urine; D006801:Humans; D007678:Kidney Glomerulus / Q000378:metabolism*; D012083:Renin / Q000652:urine*; D012084:Renin-Angiotensin System / Q000502:physiology*; D012709:Serum Albumin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D012709:Serum Albumin; D000808:Angiotensinogen; D012083:Renin