title: Acanthocytes in the urine: useful tool to differentiate diabetic nephropathy from glomerulonephritis?
abstract: OBJECTIVE
  The presence of hematuria has been suggested to indicate nondiabetic nephropathy in diabetic patients with proteinuria. However, hematuria is frequently found in patients with biopsy-proven diabetic glomerulosclerosis without nondiabetic nephropathy. Urine microscopy allows discrimination of glomerular hematuria, which is defined as acanthocyturia (urinary excretion of acanthocytes, which are dysmorphic erythrocytes with vesicle-like protrusions), from nonglomerular hematuria. We hypothesized that acanthocyturia is an uncommon finding in diabetic nephropathy, which suggests the presence of a nondiabetic nephropathy in diabetic patients with proteinuria.
  
  
  METHODS
  Urine samples of patients with the clinical diagnosis of diabetic nephropathy (n = 68), of patients with biopsy-proven glomerulonephritis (n = 43), and of age-matched healthy control subjects (n = 20) were examined by phase-contrast microscopy for the presence of hematuria (>/=8 erythrocytes/ micro l) and acanthocyturia. Acanthocyturia of >/=5% (5 acanthocytes among 100 excreted erythrocytes) was classified as glomerular hematuria; acanthocyturia of 2-4% was classified as suspected glomerular hematuria.
  
  
  RESULTS
  Hematuria was found in 62% of patients with the clinical diagnosis of diabetic nephropathy, in 84% of patients with glomerulonephritis, and in 20% of the healthy control subjects upon a single urine examination. In contrast, glomerular hematuria occurred in 4% of patients with diabetic nephropathy and in 40% of patients with glomerulonephritis (P < 0.001).
  
  
  CONCLUSIONS
  In contrast to hematuria, acanthocyturia is uncommon in patients with the clinical diagnosis of diabetic nephropathy. In diabetic patients with proteinuria, the finding of acanthocyturia points to nondiabetic glomerulopathies, and renal biopsy should be considered.
authors.affiliation: Department of Nephrology, University of Homburg, Homburg, Germany. inghei@uniklinik-saarland.de
authors.forename: Gunnar H
authors.initials: GH
authors.lastname: Heine
authors.forename: Urban
authors.initials: U
authors.lastname: Sester
authors.forename: Matthias
authors.initials: M
authors.lastname: Girndt
authors.forename: Hans
authors.initials: H
authors.lastname: Köhler
mesh_terms: D000050:Acanthocytes / Q000473:pathology*; D000368:Aged; D003404:Creatinine / Q000097:blood; D003928:Diabetic Nephropathies / Q000175:diagnosis* / Q000473:pathology / Q000652:urine; D003937:Diagnosis, Differential; D005260:Female; D005921:Glomerulonephritis / Q000175:diagnosis* / Q000473:pathology / Q000652:urine; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014556:Urine
chemical_list: D003404:Creatinine