Urinalysis



Background

  • Morning urine conc. - best anaylysis
  • ? diabetes, do 2hr post prandial
  • SG not reliable after radiol. contrast
  • UTI may give false Pos blood
  • Lab: casts, crystals, cells, & bugs
  • Tyrosine crystals = ? liver
  • Ambumin Pos in renal disease
  • Renal tubular cells seen in ATN, poisoning, pyelonephtitis and viraemia
  • Eosinophiles ATN, nephritis and UTI
  • Dilute (low SG) in Diabetes I

Normal values

  • pH – 4.5-8
  • SG – 1.005-1.025
  • Glucose - ≤7
  • Ketones – 0
  • Nitrates - 0
  • Leukocyte esterase – 0
  • Bilirubin – Negative
  • Urobilirubin – Small
  • RBC - ≤3/hpf
  • Protein - ≤8mmol
  • WBCs - ≤5 WBCs/hpf
  • Squamous epithelial cells - ≤20/hpf
  • Casts – 0-5 hyaline/lpf
  • Crystals – Occasionally
  • Bacteria/Yeast – None

FRCEM exam hints

  • Red - Propofol, chlorpromazine
  • Red - Rhabdo, UTI, porphyria
  • Orange - Vit C, carrots, rifampicin
  • Green - Asparagus, Vits B, propofol
  • Blue - Methylene blue, indomethacin, amitriptyline, cimethidine, tryptophan
  • Purple - UTI (catheterised patient)
  • Brown - Biliary dis., levodopa, metronidazole, nitrofurantoin
  • Black - Malig melanoma, Gilberts
  • White - Propofol, chyluria, pyuria, phosphate crystals++

pH

N. mildly acidic (H+ excretion).

Acidosis ↓pH

  • ↓pH - Cranberries/high-protein diet
  • Uric acid & cystine stones

Alkaline ↑pH

  • ↑pH - Fruit, low carb diet
  • Calcium oxalate/phosphate, struvite, staghorn stones
  • UTI with urea splitting proteus/klebsiella


Content by Dr Iomhar O'Sullivan. Last review Dr ÍOS 24/03/24.