title: Comparison of proteinuria determination by urine dipstick, spot urine protein creatinine index, and urine protein 24 hours in lupus patients.
abstract: BACKGROUND
  A simple, convenient, and accurate method for detecting urine protein excretion in lupus nephritis is crucial.
  
  
  OBJECTIVE
  The objectives of the study were to determine the sensitivity and the specificity of the qualitative urine dipstick test value to detect 0.50 g or greater of the quantitative 24-hour urine protein (24-hUP) in lupus patients, to evaluate an overall agreement of the dipstick test results and the magnitude of 24-hUP, and to examine the correlation between the spot urine protein creatinine index (S-UPCI) and the 24-hour UPCI with that of the 24-hUP.
  
  
  METHODS
  A prospective study was conducted in 92 patients with lupus. All dipstick test values from 5 dipstick assays (Bayer, Roche, Meditest USA, Standard Diagnostics, and Arkray) and the S-UPCI were obtained within 6 hours of the 24-hUP collection. Of 149 urine samples, only 39% were collected properly and were used for analysis.
  
  
  RESULTS
  The sensitivity and specificity of a ≥ 2+ dipstick test result to detect 0.50 g or greater 24-hUP were 56-% to 80% and 67% to 92%, respectively. The agreement of the urine dipstick test values and the magnitude of 24-hUP was fair (κ = 0.23-0.32). The correlation between the S-UPCI and the 24-hUP was 0.83 (P < 0.0001), and that of the 24-hour UPCI and the 24-hUP was 1 (P < 0.0001). Using 24-hUP 2 g/d or less, the bias ± 1.96 SD of the difference of S-UPCI and 24-hUP was 0.23 (SD, 0.96) g.
  
  
  CONCLUSIONS
  A ≥ 2+ dipstick test is relatively sensitive to detect significant proteinuria, but it is poorly correlated with quantitative 24-hUP. The S-UPCI and the 24-hUP can be used interchangeably for follow-up in lupus nephritis patients with proteinuria of less than 2 g/d.
authors: Division of Rheumatology, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors: Thanyaluk
authors: T
authors: Chotayaporn
authors: Nuntana
authors: N
authors: Kasitanon
authors: Waraporn
authors: W
authors: Sukitawut
authors: Worawit
authors: W
authors: Louthrenoo
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D008181:Lupus Nephritis / Q000150:complications* / Q000652:urine; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis* / Q000652:urine; D012680:Sensitivity and Specificity
chemical_list: D003404:Creatinine