title: Renal biopsy in lupus patients with low levels of proteinuria.
abstract: OBJECTIVE
  Early and accurate detection of kidney involvement in systemic lupus erythematosus (SLE) improves outcomes. Renal biopsy is required for definitive diagnosis of lupus nephritis (LN). In the absence of acute renal failure (ARF), moderate levels of proteinuria (> 1000 mg/24 h) have been recommended by some to justify biopsy. We investigated whether patients with lower levels of proteinuria without ARF have significant renal disease and should be routinely biopsied.
  
  
  METHODS
  We retrospectively evaluated 21 SLE patients with 24-h urine protein < 1000 mg who underwent kidney biopsies. Indications for biopsy included new-onset proteinuria, increasing proteinuria, or hematuria (> 5 red blood cells per high power field). No patient had ARF.
  
  
  RESULTS
  Sixteen of 21 (77%) biopsies were diagnostic of LN: 3 class II, 10 class III (5 superimposed class V), 2 class IV (one superimposed class V), and one with class V. One patient had thrombotic microangiopathy. The remaining 4 (23%) patients had non-lupus renal disease. Thirteen patients with class III or greater LN required alterations in therapeutic regimen because of biopsy findings. Of 7 patients without hematuria at the time of biopsy, 4 (57%) had class III, IV, or V LN. One patient without hematuria and < 500 mg/24 h proteinuria had class III LN.
  
  
  CONCLUSIONS
  We found significant renal involvement (Class III, IV, or V LN) in SLE patients with < 1000 mg proteinuria with or without hematuria. Our findings suggest that biopsy be strongly considered in this patient population.
authors.affiliation: Divisions of Nephrology and Rheumatology, Johns Hopkins University Department of Medicine, Baltimore, Maryland, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Christopher-Stine
authors.forename: Mark
authors.initials: M
authors.lastname: Siedner
authors.forename: Janice
authors.initials: J
authors.lastname: Lin
authors.forename: Mark
authors.initials: M
authors.lastname: Haas
authors.forename: Hemal
authors.initials: H
authors.lastname: Parekh
authors.forename: Michelle
authors.initials: M
authors.lastname: Petri
authors.forename: Derek M
authors.initials: DM
authors.lastname: Fine
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D042241:Early Diagnosis; D005260:Female; D006417:Hematuria / Q000473:pathology / Q000652:urine; D006801:Humans; D007668:Kidney / Q000473:pathology*; D008181:Lupus Nephritis / Q000473:pathology* / Q000652:urine; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011507:Proteinuria / Q000473:pathology* / Q000652:urine; D012189:Retrospective Studies