Urinalysis Hematuria Proteinuria

Urinalysis
Urinalysis
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Clean-catch midstream collection
Single straight catheterization
Suprapubic aspiration
Foley’s catheter
High osmolarity and low pH
– Cellular preservation
– First voided morning urine*
Routine urinalysis
Gross exam
•Color
•Turbidity
•Odor
Dipstick
•pH
•Sp gr
•Protein
•Blood
•Glucose
•Ketones
•Leukocytes
•Nitrites
•Urobilibogen
Microscopic
•Cells
•Casts
•Bacteria
•Yeast
•Parasites
•Crystals
•Artifacts
Urinalysis: Odor
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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/dL
2+ = 100 mg/dL
3+ = 300 mg/dL
4+ = >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 Æ obstructive
• Nitrite: Gm(-)bacteria convert Nitrate
• Leukocytes:
Leukocyte esterase
• False Positive
– Vaginal contamination
• False Negative
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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
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Sources: Glomerulus Æ
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
4
Postinfectious
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
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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”
Crystals
Acid Urine (pH<6)
•Uric acid
Rhombic prism form
Sodium urate
Amorphous urate
•Calcium oxalate
•Cystine
•Leucine
•Tyrosine
•Cholesterol
•Sulfa
Alkaline Urine (pH>6)
•Phosphates
Triple phosphates
Calcium phosphates
Amorphous phosphates
•Ammonium urates
Oxalate crystals
• Envelope-shaped
• Dumbbell-shaped
Triple phosphate crystals
Coffin lid-shaped
Cystine crystals
Crystals due to drugs
Both are birefringent (strongly in Indinavir)
End