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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.

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Microscopic Urinalysis

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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

  • Centrifuge 10 ml of well-mixed urine specimen (1500-2000 rpm) for 5 minutes.

  • Suction or pour off all but 1.0 ml of urine

  • 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).

Specific Gravity1.020

pH range4.8 - 7.5




Urobilinogen0.8 EUs


Occult BloodNegative

WBC EsteraseNegative







0-1 Hyaline Cast

Few Bacteria


Few Ca oxalate crystals

Typical Urine Report on Normal Male

Epithelial Cells

  • Squamous epithelial cells

  • Transitional epithelial cells

  • Renal tubular epithelial cells

  • Oval Fat Bodies

  • Clue Cells

Squamous Epithelial Cells

  • 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

    • Male1-2 RBC/HPF

    • Female3-12 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

  • 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

    • 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

  • 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 Tamm-Horsfall 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



Specific Gravity1.035










Epi cellsMany

Casts2-5 Hyaline

RBCs/HPF 0-2


Crystals2-5 Triple PO4

Many Amorp Urates

BacteriaFew (10-50)

Gladys Glomerulus (35 yr old)

Tammy Tubule (25 yr old)

  • ColorYellow

  • AppearanceCloudy

  • Specific Gravity1.003

  • GlucoseNeg

  • BilirubinNeg

  • KetoneNeg

  • BloodNeg

  • pH8.5

  • Protein4+

  • Urobilinogen0.2

  • NitriteNeg

  • LeukocytesTrace

  • Epi cells5-20

  • CastsNone

  • RBCs/HPF 50-100

  • WBCs/HPF0-2

  • Crystals

  • Many Amorp Urates

  • BacteriaNone



Specific Gravity1.011










Epi cellsFew

Casts2-5 Hyaline

5-10 Fine gran

>10 Coarse gran

RBCs/HPF 2-5



Few Amorp Urates


Bowman S. Capsule (2 yr old)

Ned Nephron (23 yr old)

  • ColorAmber

  • AppearanceClear

  • Specific Gravity1.006

  • GlucoseNeg

  • BilirubinNeg

  • KetoneSmall

  • BloodMod

  • pH6.0

  • ProteinNeg

  • Urobilinogen1.0

  • NitritePositive

  • LeukocytesMod

  • Epi cells>100

  • CastsNone

  • RBCs/HPF None

  • WBCs/HPF25-50

  • CrystalsNone

  • BacteriaMod (50-200)

  • OtherBudding yeast

Renal Diseases

  • 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).

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