Microscopic Urinalysis
Vicki S. Freeman, Ph.D
Clinical Laboratory Methods
General Considerations
• The results of the microscopic should
correlate with physical and chemical test
results.
• Contamination is common; especially in
voided specimens when no effort is made to
obtain a “clean catch” specimen.
• Results more reliable with concentrated, but
fresh specimen, as cellular elements tend to
lyse in dilute, hypotonic urine or alkaline
urine.
More General Considerations
• Urine should be examined within one hour
of collection. If not, specimen should be
refrigerated.
• Normal values vary considerably due to
variation in concentration of the specimen
and different methods used to concentrate
the sediment by centrifugation (volume,
speed, etc.)
Sediment Preparation & Procedure
1 Centrifuge 10 ml of well-mixed urine
specimen (1500-2000 rpm) for 5 minutes.
2 Suction or pour off all but 1.0 ml of urine
3 Resuspend sediment and place
approximately .05 ml on a glass slide - add
coverslip on top
Sediment Preparation & Procedure
• Examine under low power with dimmed
light or with phase contrast microscopy to
estimate urine sediment (casts and crystals).
Report numbers per low power field (LPF).
• Examine under high power objective to
estimate #s of RBCs, WBCs, and renal
tubular epithelial cells (RTE); report per
high power field (HPF).
Typical Urine Report
on Normal Male
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Specific Gravity
pH range
Protein
Glucose
Ketones
Urobilinogen
Bilirubin
Occult Blood
WBC Esterase
Nitrite
1.020
4.8 - 7.5
Negative
Negative
Negative
0.8 EUs
Negative
Negative
Negative
Negative
• Color
• Appearance
Straw
Clear
• Microscopic
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0-8 WBC/HPF
0-2 RBC/HPF
0-1 Hyaline Cast
Few Bacteria
0-1 RTE/HPF
Few Ca oxalate crystals
Epithelial Cells
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Squamous epithelial cells
Transitional epithelial cells
Renal tubular epithelial cells
Oval Fat Bodies
Clue Cells
Squamous Epithelial Cells
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30-50 microns
large, flat cells with small nuclei
Appear flat with abundant cytoplasm
Originate from the superficial lining of the
urethra and vagina
• Common contaminant; seen in female
voided specimen
Transitional epithelial cells
• 20 -30 microns
• Polyhedral shaped but swell in urine to
spheroidal shape
• Have round or pear-shaped contours with
small central nucleus (may be bi-nucleated)
• Originate from transitional epithelial lining
of the renal pelvis, ureter, urinary bladder
and proximal urethra
• A few are seen in normal urine; large clumps
suggest possible carcinoma.
Renal tubular epithelial cells (RTE)
• 14 - 60 microns from proximal and distal
convoluted tubules
• Single, oblong or egg-shaped cells with
coarsely granular eosinophilic cytoplasm
• Nuclei may be multiple but are small with
dense chromatin
• Seen in cases of acute tubular necrosis and
drug or heavy metal toxicity
Oval Fat Bodies
• Renal tubular cells that have absorbed lipids.
• Are highly refractile and produce a
characteristic Maltese cross appearance with
polarized light.
• Extremely significant finding. Seen in lipid
nephrosis and terminal kidney disease.
Clue Cells
• Squamous epithelial cells covered with
coccobacilli, Gardnerella vaginalis
Blood Cells
• Red Blood Cells
• White Blood Cells
Red Blood Cells
• Normal size 6-8 microns, biconcave discs
• Swollen in hypotonic, crenated in
hypertonic urine
• Empty RBC membranes may be seen from
lyzed cells in alkaline urine
• Confusing artifacts
• oil droplets, yeast, urates
Red Blood Cells
• Normal
– Male
– Female
1-2 RBC/HPF
3-12 RBC/HPF
• Increased RBC seen in
– Renal disease such as glomerulonephritis, lupus
nephritis, kidney stones, tumors and trauma
– Lower urinary tract disease such acute and
chronic infection, tumors and strictures
– Extrarenal disease such as acute appendicitis.
White Blood Cells
• 10-12 microns, swell to 15 microns in
alkaline or hypotonic urine, nuclei more
distinct in acid urine
• Mainly neutrophils and have a granular
cytoplasm and lobed nucleus
White Blood Cells
• Normal 0-8 WBC/HPF
• Increased in
– pyelonephritis, cystitis, urethritis, prostatitis
• “Glitter cell” term used to describe large
WBC seen in hypotonic urine that have
Browian movement of granules in
cytoplasm
• Clumps of WBCs considered very
significant in indicating an infection
Other Urinary Elements
• Bacteria
• Yeast
– confused with red cells
– look for budding,
doubly refractive wall
• Trichomonas
– confused with white cells
– look for undulating
membrane movement
• Sperm
Urine Casts
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Hyaline Casts
Red Blood Cell Casts
Hemoglobin or Blood Cell Casts
White Blood Cell Casts
Renal tubular epithelial cell casts
Granular casts
Waxy casts
Fatty casts
Urinary Casts
• Cylindrical structure which consists of
– jelled protein (Tamm-Horsfall mucoprotein)
– clumping of the protein or conglutination of material
within the lumen of the renal tubules
– Albumin or globulins may be mixed with the
mucoprotein
• Conditions that increase urine cast formation
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Increased concentration of the urine]
Increased acidity of the urine
High protein concentration in the urine
Stasis or obstruction of the nephrons by cells or debris
Hyaline Casts
• Formed in the lumen of the distal
convoluted tubules or collecting ducts and
serve as the matrix of all casts
• Pale, smooth and usually cylindrical,
homogeneous gel-like forms of low
refractive index. Mainly Tamm-Horsfall
mucoprotein
• Narrower casts form in the convoluted
tubules while broader casts form in the
collecting ducts.
Red Blood Cell Casts
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These casts are always pathologic
Diagnostic of glomerular disease or damage
Classically found in acute glomerulonephritis
RBC outline must be sharply defined in at
least part of the cast
Hemoglobin Cast
• An RBC cast in which the red cells have
ruptured and disintegrate
• Cast appears reddish-brown due to acid
hematin formation
• Diagnostic of glomerular disease or damage
such as acute glomerulonephritis
WBC Cast
• Hyaline cast with WBCs embedded in
matrix
• Indicate inflammation/infection in kidney
• Seen in acute pyelonephritis and other
nephritis conditions
Renal Tubular Epithelial Cast
• Hyaline cast with renal tubular epithelial
cells embedded in the hyaline matrix
• Form as result of stasis and necrosis of the
tubules
• Seen in severe chronic renal disease,
exposure to nephrotoxic agents or viruses
and rejection in kidney transplants
Granular Casts
• Results of the degeneration of cellular
components of casts or direct aggregation of
serum proteins into a matrix of TammHorsfall mucoprotein
• Usually indicates significant renal disease
• Thought to be the result of breakdown of
cellular casts with the progression of
cellular to coarsely to finely granular to
waxy.
Waxy Casts
• Smooth, homogeneous, highly refractive
appearance. Typically have blunt, broken
ends and cracked or serrated edges
• Seen in patients with severe chronic renal
failure, malignant hypertension, diabetic
nephropathy
• May also be seen in acute renal disease and
renal allograft rejection
Fatty Casts
• Casts that have incorporated either free fat
droplets or oval fat bodies.
• In the fat is cholesterol, the droplets will be
demonstrate a “Maltese cross” appearance
under polarized light.
• Droplets which consist of triglycerides or
neutral fat will not polarize but will stain
with Sudan III or Oil Red O stains for fat.
Crystals seen in Acidic Urine
• Calcium oxalate
– envelope, dumbbell or ring forms
– colorless, do not polarize
– Common cause of kidney stones
• Uric acid
– rhombic plates, rosettes, wedges, needles
– polarize to multicolored
– found in gout
• Amorphous urates
– clumps of brownish-yellow granules
Crystals seen in Alkaline Urine
• Triple phosphate
– Coffin lid crystals
– colorless prisms
• Ammonium biurate
– thorn-apple crystals
– yellow-brown, spicule covered spheres
Crystals with Pathogenic
Significance
• Cystine
– colorless hexagonal plates
– do not polarize
– associated with inborn errors of metabolism
• Cholesterol
– rectangular plate with a notched
corner or edge
– polarize as multicolored plates
– seen in nephritis and nephrosis conditions
Gladys Glomerulus (35 yr old)
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Color
Appearance
Specific Gravity
Glucose
Bilirubin
Ketone
Blood
pH
Protein
Urobilinogen
Nitrite
Leukocytes
Pale
Clear
1.035
Neg
Neg
Neg
Neg
5.0
1+
0.2
Neg
Trace
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Epi cells
Many
Casts
2-5 Hyaline
RBCs/HPF
0-2
WBCs/HPF
10-25
Crystals 2-5 Triple PO4
Many Amorp Urates
• Bacteria Few (10-50)
Tammy Tubule (25 yr old)
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Color
Appearance
Specific Gravity
Glucose
Bilirubin
Ketone
Blood
pH
Protein
Urobilinogen
Nitrite
Leukocytes
Yellow
Cloudy
1.003
Neg
Neg
Neg
Neg
8.5
4+
0.2
Neg
Trace
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Epi cells
5-20
Casts
None
RBCs/HPF
50-100
WBCs/HPF
0-2
Crystals
Many Amorp Urates
• Bacteria
None
Bowman S. Capsule (2 yr old)
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Color
Appearance
Specific Gravity
Glucose
Bilirubin
Ketone
Blood
pH
Protein
Urobilinogen
Nitrite
Leukocytes
Yellow
Hazy
1.011
Neg
Neg
Neg
Neg
5.0
Neg
0.2
Pos
Mod
• Epi cells
Few
• Casts
2-5 Hyaline
5-10 Fine gran
>10 Coarse gran
• RBCs/HPF
2-5
• WBCs/HPF
None
• Crystals
Few Amorp Urates
• Bacteria
None
Ned Nephron (23 yr old)
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Color
Appearance
Specific Gravity
Glucose
Bilirubin
Ketone
Blood
pH
Protein
Urobilinogen
Nitrite
Leukocytes
Amber
Clear
1.006
Neg
Neg
Small
Mod
6.0
Neg
1.0
Positive
Mod
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Epi cells
>100
Casts
None
RBCs/HPF
None
WBCs/HPF
25-50
Crystals
None
Bacteria Mod (50-200)
Other
Budding yeast
Renal Diseases
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Nephrosis
Cystitis
Acute pyelonephritits
Acute glomerulonephritis
Sediment Procedure
 Centrifuge 10 ml of well-mixed urine specimen (1500 2000 rpm) for 5 minutes
 Pour off all but 1.0 ml of the urine
 Resuspend sediment and place approximately 0.05 ml on a
glass slide and add coverslip
 Examine under low power with dimmed light to estimate
urine sediment (casts and crystals). Report numbers per
low power field (lpf)
 Examine under high power to estimate #s of RBCs, WBCs
and renal tubular epithelial cells; report per high power
field (hpf).