Urinalysis: Addis Count and Specimen Prep

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Questions and Answers

What is the normal value range for RBCs in an Addis count?

0 to 2,000,000 cells/uL

0 to 1,000,000 cells/uL

0 to 100,000 cells/uL

0 to 500,000 cells/uL (correct)

During the specimen preparation for microscopic analysis of urine, what is done after centrifuging the urine?

Add a staining reagent to the sediment

Decant the supernatant carefully (correct)

Dilute the supernatant with saline

Measure the pH of the sediment

Why is RCF used instead of RPM in the procedure?

RCF is easier to calculate than RPM

RCF accounts for differences in centrifuge head diameters (correct)

RCF is necessary for accurate temperature control

RCF provides a more exact measurement of sedimentation

What volume of sediment should be placed on the microscopic slide for analysis?

20 µL (0.02 mL) Signup and view all the answers

How should the microscopic slide be covered after placing the sediment?

With a glass cover slip (22x22 mm) Signup and view all the answers

What is the average diameter of white blood cells?

12 um Signup and view all the answers

In hypotonic urine, what appearance do neutrophils exhibit?

Spherical balls Signup and view all the answers

What percentage of eosinophils in urine is considered significant?

1% Signup and view all the answers

Which type of white blood cell predominates in urine during renal transplant rejection?

Lymphocytes Signup and view all the answers

What is the normal range of white blood cells in urine for females?

0-8 WBC/hpf Signup and view all the answers

What staining result is typical for glitter cells when stained with Sternheimer-Malbin stain?

Light blue Signup and view all the answers

What occurs to leukocytes in hypertonic urine?

They become smaller without crenating Signup and view all the answers

What notable characteristic is observed in squamous epithelial cells from urine?

They have distinct cell borders Signup and view all the answers

What does the presence of WBC casts primarily indicate?

Pyelonephritis Signup and view all the answers

Which method is best for confirming the presence of bacterial casts?

Gram stain on sediment Signup and view all the answers

In which condition are fatty casts most frequently associated?

Nephrotic syndrome Signup and view all the answers

What appearance do waxy casts typically have?

Brittle with jagged ends and notches Signup and view all the answers

What condition may cause granular casts to appear in urine?

Strenuous exercise Signup and view all the answers

Which of the following describes the appearance of waxy casts when stained with supravital stains?

Homogenous, dark pink Signup and view all the answers

What distinguishes bacterial casts from WBC casts in urinary sediment?

Presence of bacilli in the protein matrix Signup and view all the answers

What is a common feature of granular casts under microscopy?

May have pathologic or nonpathologic significance Signup and view all the answers

What do broad casts indicate in renal failure?

Widening of tubular walls Signup and view all the answers

What is a characteristic of granular, dirty brown casts?

They indicate renal failure due to hemoglobin degradation. Signup and view all the answers

Which type of casts are included in the classification of urinary casts as pigmented?

Bilirubin cast Signup and view all the answers

Which of the following best describes the formation of broad casts?

They result from tubular distension and extreme urine stasis. Signup and view all the answers

What is the primary cause of granular, dirty brown casts?

Acute tubular necrosis from hemoglobinuria Signup and view all the answers

Which cast can be misdiagnosed due to other materials present, such as fecal debris?

Broad cast Signup and view all the answers

Which type of cast is least likely to be associated with renal tubular epithelial cells?

Broad cast Signup and view all the answers

Which of the following represents a common source of error in identifying granular casts?

Clumps of small crystals Signup and view all the answers

What characteristic feature distinguishes clue cells?

Granular, irregular appearance Signup and view all the answers

Which type of epithelial cell is recognized for its varying shapes and sizes based on its renal tubule origin?

Renal tubular epithelial cells Signup and view all the answers

What abnormal characteristic in transitional epithelial cells may indicate malignancy or viral infection?

Vacuoles and irregular nuclei Signup and view all the answers

Which feature is unique to renal tubular epithelial cells from the proximal convoluted tubule (PCT)?

Large size and rectangular shape Signup and view all the answers

In comparison to transitional epithelial cells, how do renal tubular epithelial cells differ in appearance?

They exhibit straight edges Signup and view all the answers

What is one of the significant implications of an increase in transitional epithelial cells following invasive urologic procedures?

It is usually of no clinical significance Signup and view all the answers

Which of the following shapes are transitional epithelial cells NOT likely to exhibit?

Cuboidal Signup and view all the answers

What distinguishes collecting duct renal tubular epithelial cells from other types?

They are cuboidal and never round Signup and view all the answers

Study Notes

Addis Count

Standard procedure for quantifying formed elements in urine.
Uses a hemocytometer for analysis.
Normal values:
- RBCs: 0 to 500,000 cells/uL
- WBCs and Epithelial cells: 0 to 1,800,000 cells/uL
- Hyaline casts: 0 to 5000 cells/uL

Specimen Preparation

10-15 mL of urine is centrifuged at 400 RCF for 5 minutes.
The supernatant is decanted, leaving the sediment.
0.5-1.0 mL of sediment is placed on a microscopic slide with a coverslip.
The sample is viewed under a microscope with bright field illumination and reduced lighting.

White Blood Cells

Larger than RBCs, averaging 12 um in diameter.
Increased urinary WBCs (pyuria or leukocytoruia) indicate conditions such as bacterial infection (UTI), interstitial nephritis, and SLE.
Neutrophils are the primary WBC type found in urine.
Neutrophils can degenerate in dilute alkaline urine, losing nuclear detail.
In hypotonic urine, WBCs swell and become spherical, leading to rapid lysis (up to 50% within 2-3 hours at room temperature). These are known as "glitter cells" due to granular movement.
In hypertonic urine, WBCs shrink but do not crenate. They also develop finger-like projections (myelin forms) due to cell membrane breakdown.
Eosinophils are rare in urine, but their presence (more than 1%) suggests drug-induced interstitial nephritis, UTI, or renal transplant rejection.
Lymphocytes are predominant in urine during renal transplant rejection.
Normal range in urine: 0-5 WBC/hpf in males and 0-8 WBC/hpf in females.

Epithelial Cells

Squamous Epithelial Cells:
- Originate from the vagina, female urethra, and lower male urethra.
- Largest cells in urine sediment, with abundant, irregular cytoplasm and a prominent nucleus.
- May appear flagstone-shaped with distinct cell borders.
- Clue cells: Pathological squamous cells covered with Gardnerella vaginalis bacteria, giving a granular and irregular appearance.
- Increased amounts are more common in females.
Transitional Epithelial (Urothelial) Cells / Bladder Epithelial Cells:
- Originate from the renal pelvis, calyces, ureters, bladder, and upper male urethra.
- Smaller than squamous cells, exhibiting spherical, polyhedral, and caudate forms.
- Can absorb large amounts of water.
- Increased numbers after invasive urologic procedures are insignificant.
- Abnormal morphology (vacuoles, irregular nuclei) could indicate malignancy or viral infection.
Renal Tubular Epithelial Cells (RTE Cells):
- Vary in size and shape depending on the origin within the renal tubules.
- Proximal convoluted tubule (PCT) cells are larger and rectangular (columnar or convoluted cells).
- Distal convoluted tubule (DCT) cells are smaller and round or oval.
- Collecting duct RTE cells are cuboidal and never round.
- Differentiated from transitional cells by an eccentrically placed nucleus and at least one straight edge.
- Groups of three or more collecting duct cells are called renal fragments.
- Associated with pyelonephritis (upper UTI) and are a primary marker for differentiating pyelonephritis from cystitis (lower UTI).
- Also present in non-bacterial inflammations like acute interstitial nephritis and glomerulonephritis.

Urinary Casts

Hyaline Casts:
- Homogenous, clear, and colorless.
- Composed primarily of protein, usually Tamm-Horsfall protein.
- Appear in low numbers under normal conditions.
- Increased numbers can indicate conditions like glomerulonephritis, pyelonephritis, and congestive heart failure.
- May be confused with mucus threads, fibers, hair, or artifacts depending on lighting.
Red Blood Cell Casts:
- Indicate bleeding within the nephron.
- Associated with glomerulonephritis, vasculitis, and trauma.
- May break down in alkaline urine or appear as clumps of RBCs.
White Blood Cell Casts:
- Indicate inflammation or infection within the nephron.
- Typically associated with pyelonephritis or interstitial nephritis.
- Best observed under low power magnification.
- Must be positively identified under high power to differentiate from epithelial cells.
- Staining and phase microscopy can enhance nuclear details.
Bacterial Casts:
- Contain bacteria within the protein matrix.
- Associated with pyelonephritis.
- Confirmation is achieved with Gram stain on dried or cytocentrifuged sediment.
Fatty Casts:
- Contain fat droplets within the matrix.
- Associated with disorders causing lipiduria, including nephrotic syndrome, toxic tubular necrosis, diabetes mellitus, and crush injuries.
- Confirmation is accomplished through polarized microscopy and fat staining (Sudan III or Oil Red O).
Granular Casts:
- Contain cellular debris, granules, or lysosomal enzymes.
- Coarsely granular casts may indicate acute tubular necrosis.
- Finely granular casts can be non-pathologic or indicate chronic processes.
- Visible under low power, but final identification requires high power to confirm presence of a cast matrix.
- Pathologic increase: glomerulonephritis and pyelonephritis.
- Physiologic increase: strenuous exercise.
Waxy Casts:
- Denote severe stasis and chronic renal failure.
- Brittle, highly refractive, and often fragmented.
- Have a ground glass appearance with cracks or fissures.
- Stain homogenous dark pink with supravital stains.
- More easily visualized than hyaline casts due to higher refractive index.
Broad Casts:
- Indicate tubular distension or severe stasis.
- Represent destruction of tubular walls.
- Can form in the collecting ducts.
- Can occur in any cast type.
- Associated with chronic renal failure and biliary obstruction.
- Bile-stained broad waxy casts are seen in tubular necrosis caused by viral hepatitis.
Granular Dirty Brown Casts:
- Contain hemoglobin degradation products (methemoglobin), indicating acute tubular necrosis.
- Associated with toxic effects of massive hemoglobinuria which can lead to renal failure.
- Must be present alongside other pathologic findings (RTE cells, positive blood reagent strip).

Sources of Error

Hyaline Casts: Mucus threads, fibers, hair, and increased lighting.
RBC Casts: RBC clumps.
WBC Casts: WBC clumps.
Bacterial Casts: Granular casts.
Epithelial/RTE Casts: WBC casts.
Granular Casts: Artifacts like clumps of small crystals, fecal debris, and columnar RTE cells.
Waxy Casts: Cotton threads or diaper fibers, fibers, and fecal material.
Fatty Casts: Fecal debris.
Broad Casts: Fecal material and fibers.

Classification of Urinary Casts (Brunzel, 3rd Ed.)

Homogenous: Hyaline and waxy casts.
Pigmented: Bilirubin, myoglobin, and hemoglobin.
Size: Broad casts.
Inclusions:
- Cellular inclusions: RBCs, WBCs, RTE cells, mixed cells, and bacteria.
- Others: Granular, fat globules (cholesterol and triglycerides), hemosiderin granules, crystals.

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Description

This quiz covers the standard procedure for quantifying formed elements in urine using the Addis Count method. It includes specifics on specimen preparation and details about white blood cells, including their significance in urinary analysis. Test your knowledge on normal values and the effects of urine on WBC morphology.