nephrology urinalysis lecture 2 10

  • best collected first morning void (most concentrated and acidic)

UA components

  • specific gravity: how concentrated urine is
    • water: 1.000
    • concentrated urine >1.02
    • very concentrated >1.04
  • Heme
    • in hemolysis, rhabdo from myoglobin, rbc from hematuria
  • Protein
    • small amount of urine protein can be from tubule <3g/day

    • 3 g/day is nephrotic proteinuria, suggest glomerular disorder

  • RBC/WBC
      • rbc cast with biconcave shape
      • leaking blood from glomerulus and makes casts in tubule
      • seen in glomerulonephritis and vasculitis but not in lower urinary tract (beyond kidney)
      • WBC casts, bigger than RBC
      • seen in pyelo but not cystitis
      • AIN: PPI, abx. Sterile pyuria, fever, eosinophilia, rash
  • urine eosinophils: not helpful
  • Hyaline cast
    • uromodulin protein, normal
  • Renal tubular epithelial cells
    • ATN
  • Granular casts
    • ATN
    • damage to tubular cells
      • break off, slough, form cast
  • Oval fat bodies: nephrotic syndrome
  • Calcium oxalate crystals: acidic urine
    • ingestions: ethylene glycol
    • can be normal
  • Urate crystals
  • Triple phosphate
    • struvite stones
  • Yeasts

Automated UA

  • iQ200 and Cobas

Pre-renal Failure

  • prior to glomerulus
  • volume depletion
  • high Bun/Cr
  • concentrated urine, hyaline casts

Intrinsic

  • Glomerular
    • proteinuria
    • hematuria, RBC casts
  • Tubular

ATN

  • Intrinsic
  • Interstium or tubule
  • UA: at least 1 granular cast, at least one renal tubular epithelial cells

Interstitial nephritis

  • interstial nephritis
  • allergic issues
  • eosinophiluria not diagnostic
  • pyuria not helpful

Postrenal

  • obstruction
  • Chronic renal failure
    • Hx of HTN, serum Cr, proteinuria, small kidneys on US
  • UA only picks up albumin. UPC helpful to pick up myeloma and amyloid

Examples