Lab

Urine Protein to Creatinine Ratio

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Urine Protein to Creatinine Ratio

  • Indication
  1. Proteinuria evaluation and monitoring
  2. Chronic Kidney Disease diagnosis
  • Efficacy
  1. More accurate than 24 Hour Urine Protein collection
  2. Most accurate if first morning void is used
  3. Urine Albumin to Creatinine Ratio is preferred over Urine Protein to Creatinine Ratio
    1. Urine Albumin to Creatinine Ratio has higher Test Sensitivity (see below)
    2. Consider Urine Protein ratio when Urine Albumin to Creatinine Ratio is high (>300 mg/g)
  • Technique
  • Random urine collection
  1. Urine Creatinine in mg
  2. Urine Protein in mg
  3. Calculate Urine Protein mg to Urine Creatinine mg Ratio
  1. Consider when Urine Albumin to Creatinine Ratio is high (>300 mg/g)
  2. Lower efficacy than Urine Albumin to Creatinine Ratio
    1. Lower Test Sensitivity than Urine Albumin to Creatinine Ratio for low level Proteinuria (<150 mg/24 hours)
    2. Also measures Proteins unrelated to primary Kidney disease (e.g. Multiple Myeloma)
  3. Child under age 2 years
    1. Normal Ratio <0.5
  4. Adults and children over age 2 years
    1. Normal ratio <0.2 grams Protein per gram Creatinine
    2. Nephrotic Ratio >3.5 grams Protein per gram Creatinine
  5. Estimation of total Protein
    1. Total Protein (g/m2/day) = Upr/Cr * 0.63
    2. Abitbol (1990) J Pediatr 116(2): 243-7 [PubMed]
  6. False Positive causes (unrelated to Kidney disease)
    1. Tubular secreted Proteins (Tamm-Horsfall Protein)
    2. Plasma Proteins (Multiple Myeloma, Infectious disease)
  • References
  1. Ruggenenti (1998) BMJ 316:504-9 [PubMed]
  2. (2002) Am J Kidney Dis 39:S1 [PubMed]