urinalysis hematuria proteinuria - department of medicine
TRANSCRIPT
Urinalysis
Urinalysis
• Clean-catch midstream collection• Single straight catheterization• Suprapubic aspiration• Foley’s catheter• High osmolarity and low pH
– Cellular preservation– First voided morning urine*
Routine urinalysisGross exam Dipstick Microscopic•Color •pH •Cells•Turbidity •Sp gr •Casts•Odor •Protein •Bacteria
•Blood •Yeast•Glucose •Parasites•Ketones •Crystals•Leukocytes •Artifacts•Nitrites•Urobilibogen
Urinalysis: Odor
• Ammonia: bacterial contamination• Fruity: ketones (diabetes, starvation)• Maple syrup: maple syrup urine disease• Musty: phenylketonuria• Ingested foods: asparagus• Excreted drugs: antibiotics
Urine: physical properties
• Yellow (urochrome)• Clear• Specific gravity
– Inaccurate surrogate for osmolarity– 1.001-1.035 ~ 50-1000 mOsm/kg– 1.010 ~ “Isosthenuria”– Used to determine concentrating ability
Urine: chemical properties
• Dipstick methodology• pH: 4.5-8 • Protein: Trace = 5-20 mg/dL
1+ = 30 mg/dL2+ = 100 mg/dL3+ = 300 mg/dL4+ = >2000 mg/dL
• Blood: peroxidase activity of Hgb
Urine pH
• Normal range 4.5-8.5– pH > 7.5 : taking bicarbonate, alkali suppl– pH 8-9 : urea-splitting bacteria
• Acidosis with urine pH > 6.0, suggests RTA
• Amorphous crystal type depends on pH– pH 4.5-6.0: urates– pH >6.5: phosphates
• pH can rise in open container (CO2 loss)
Urine: chemical properties
• Glucose: • Ketones: Acetoacetate (++), acetone (+)
NOT β-hydroxybutyrate• Urobilinogen: Ehrlich reaction• Bilirubin: Only conjugated obstructive• Nitrite: Gm(-)bacteria convert Nitrate• Leukocytes:
Leukocyte esterase
• False Positive– Vaginal contamination
• False Negative– High glucose– Albumin– Ascorbic acid– Tetracycline– Cephalexin– Oxalic acid
Nitrite
• False negative– Inadequate bladder retention time (it may take
up to 4 hrs to convert nitrate to nitrite)– Prolonged storage of sample– Several uropathogens do not convert nitrate
to nitrite• Streptococcus faecalis, other gram positive
Microscopic examination
• “Spun” urine sediment• Centrifuge @ 1500-2000 rpm x 5 mins
Erythrocytes• Sources: Glomerulus
urethra• >2-3 rbc/HPF = pathologic• Crenated in hypertonic urine• Dysmorphic rbc’s ~ glomerular
pathology
Leukocytes• Larger than rbc• Nucleated cells/granules• Glitter cells (granules brownian motions)
Leukocytes
• R/O contamination• Mostly PMN’s, but also look for
Eosinophils• Staining for eosinophils
– Wright stain – Hansel stain (improves the
sensitivity and PPV)
Diseases Associated with Eosinophiluria
Urine Stain
N Hansel Wright
AIN 11 10 2
RPGN 10 4 4Postinfectious 6 1 1
ATN 30 0 0
Acute pyelo 10 0 0
Acute prostatitis
10 6 2
Nolan III RC et al: NEJM 1986;315:1516-19
Renal tubular epithelial cells• Larger than PMN’s• Few cells can be found in
normal urine• Indicate tubular damage or
inflammation from ATN or interstitial nephritis
Casts
…Tamm-Horsfall glycoprotein“Uromodulin”
RBC cast formation
Granular casts
• Fine granular casts– Serum proteins
• Coarse granular casts– Degeneration of embedded cells
• “Non-specific” but “pathologic”
CrystalsAcid Urine (pH<6) Alkaline Urine (pH>6)•Uric acid •Phosphates
Rhombic prism form Triple phosphatesSodium urate Calcium phosphatesAmorphous urate Amorphous phosphates
•Calcium oxalate •Ammonium urates•Cystine•Leucine•Tyrosine•Cholesterol•Sulfa
Oxalate crystals• Envelope-shaped• Dumbbell-shaped
Triple phosphate crystalsCoffin lid-shaped
Cystine crystals
Crystals due to drugs
Both are birefringent (strongly in Indinavir)
End