Urine

Proteinuria in Adults

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Proteinuria in Adults, Proteinuria

  • Pathophysiology
  1. Glomerulus is permeable
    1. Molecular Weight under 60,000 Daltons may be filtered
    2. Albumin (MW 65,000) should not be filtered
  2. Normal Urinary Protein Excretion <150 mg/day
    1. Immunoglobulin (20,000 Daltons) 20%
    2. Albumin (65,000 Daltons) 40%
    3. Tamm-Horsfall Mucoprotein (distal tubule secrete) 40%
  • Causes
  • Labs
  • Step 1
  1. Qualitative Protein: Random dipstick Urinalysis
    1. Obtain first morning void
    2. See Urine Protein
    3. Confirm Proteinuria with Sulfosalicylic Acid Test or quantitative protein in step 2
  2. Microscopic Urinalysis findings of renal disease
    1. Urine fats (Nephrotic Syndrome)
    2. Urine WBCs without bacteruria (Renal Interstitial)
    3. Dysmorphic erythrocytes (Glomerular disease)
    4. Cellular or Granular Casts (chronic renal disease)
    5. Urine Eosinophils
      1. Drug-induced Acute Interstitial Nephritis
  3. Criteria for Step 2 evaluation below
    1. Nephrology consult for positive microscopic findings
    2. Urinalysis with 3+ to 4+ Urine Protein
    3. Urine Protein trace to 2+ on 2-3 Urinalysis in 1 month
      1. Repeat if related to transient cause (e.g. UTI, Exercise, Fever, CHF, Dehydration)
  • Labs
  • Step 2
  1. Quantitative Protein (2 samples within 3-6 months) severe cutoffs
    1. Urine Albumin to Creatinine Ratio (random urine) 500-1000 mg/g or
    2. Urine Protein to Creatinine Ratio (random urine) 300 mg/g or
    3. Urine Protein 24 Hour collection 2 grams/day
  2. Interpretation of 24 Hour Urine Protein Excretion or Albumin to Creatinine Ratio
    1. Severe Proteinuria, Macroalbuminuria criteria met
      1. Nephrology Consultation
      2. Determine Creatinine Clearance
      3. Monthly monitoring (see below)
    2. Proteinuria level below cutoffs listed above
      1. Determine Creatinine Clearance
      2. Creatinine Clearance normal
        1. Orthostatic Proteinuria
          1. Consider in age under 30 years
          2. Collect Split 24 Hour Urine Protein
        2. Isolated poteinuria
        3. Recheck every 6 months
      3. Creatine Clearance decreased
        1. Consider nephrology Consultation
        2. Monthly monitoring (see below)
  • Monitoring
  1. Frequency (see lab protocol above)
    1. Orthostatic Proteinuria: every 1-2 years
    2. Isolated Proteinuria (<2 grams/day): every 6 months
    3. Large Proteinuria (>2 grams/day): every month
  2. Testing
    1. Blood Pressure
    2. Urinalysis
    3. Renal Function test
  3. Nephrology Consultation criteria (see lab protocol)
    1. Large Proteinuria (>2 grams/day)
    2. Urine microscopy positive for signs of renal disease
    3. Renal Insufficiency (decreased Creatinine Clearance)
  • References
  1. Carroll (2000) Am Fam Physician 62:1333-40 [PubMed]
  2. Molitch (2004) Diabetes Care 27(suppl 1): S79-S83 [PubMed]
  3. Dornbrand (1992) Adult Ambulatory Care, p. 270-4
  4. Friedman (1991) Problem Oriented Diagnosis, p. 261-3