title: Urinary protein/creatinine ratio versus 24-hour proteinuria in the evaluation of lupus nephritis.
abstract: BACKGROUND
  The urinary protein/creatinine ratio has been used instead of 24-hour proteinuria in Nephrology practice for the follow-up of glomerular diseases, considering the advantages of collection and the low cost. However, there are still doubts as to its applicability both for an isolated evaluation and for the follow-up of patients with lupus nephritis.
  
  
  OBJECTIVE
  To evaluate 24-hour proteinuria determinations and random urine samples, performing urinary creatinine correction and urinary protein/creatinine ratio in subjects with lupus nephritis.
  
  
  METHODS
  24-hour proteinuria and urinary protein/creatinine ratio were determined by conventional methods (automated Pyrogallol for proteinuria and alkaline picrate for creatinine).
  
  
  RESULTS
  Seventy-eight urine samples of 41 patients diagnosed with systemic lupus erythematosus, according to the American Rheumatology Association, with lupus nephritis, were analyzed, and a good correlation between 24-hour proteinuria and urinary protein/creatinine ratio (r = 0.9010 and r² = 0.813) was observed. However, a poor correlation between random proteinuria (without creatinine correction) versus 24-hour proteinuria (r = 0.635 and r² = 0.403) or versus urinary protein/creatinine ratio (r = 0.754 and r² = 0.569) was seen.
  
  
  CONCLUSIONS
  24-hour proteinuria and urinary protein/creatinine ratio were useful in the follow-up of each case. However, we observed that the absolute values were different, which did not allow the replacement of one for the other during follow-up, especially when this result is used to define the activity of the disease. Based on these results, we suggest a period of intersection from one to the other (two to three determinations by both methods), and the choice of one marker for proteinuria follow-up, if necessary.
authors.affiliation: Setor de Glomerulopatias, Universidade Federal de São Paulo.
authors.forename: Grace Tamara Moscoso
authors.initials: GT
authors.lastname: Solorzano
authors.forename: Marcus Vinicius Madureira E
authors.initials: MV
authors.lastname: Silva
authors.forename: Sílvia Regina
authors.initials: SR
authors.lastname: Moreira
authors.forename: Sonia Kiyomi
authors.initials: SK
authors.lastname: Nishida
authors.forename: Gianna Mastroianni
authors.initials: GM
authors.lastname: Kirsztajn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D008181:Lupus Nephritis / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000652:urine*; D013997:Time Factors; D055815:Young Adult
chemical_list: D003404:Creatinine