Copyright © 2014. F.A. Davis Company CHAPTER 6 MICROSCOPIC EXAMINATION OF URINE

Copyright © 2014. F.A. Davis Company

CHAPTER 6CHAPTER 6

MICROSCOPIC EXAMINATION MICROSCOPIC EXAMINATION OF URINEOF URINE


Upon completing this chapter, the reader will be able to

1.List the physical and chemical parameters included in macroscopic urine screening, and state their significance.2.Discuss the advantages of commercial systems over the glass-slide method for sediment examination.3.Describe the recommended methods for standardizing specimen preparation and volume; centrifugation; sediment preparation, volume, and examination; and reporting results. 4.State the purpose of Sternheimer-Malbin, acetic acid, toluidine blue, Sudan III, Gram, Hansel, and Prussian blue stains in the examination of urine sediment.5.Identify specimens that should be referred for cytodiagnostic testing.

Learning ObjectivesLearning Objectives


6. Describe the basic principles of bright-field, phase-contrast, polarizing, dark-field, fluorescence, and interference-contrast microscopy, and their relationship to sediment examination.

7. Differentiate between normal and abnormal sediment constituents.8. Discuss the significance of red blood cells (RBCs) in urine sediment.9. Discuss the significance of white blood cells (WBCs) in urine

sediment.10.Name, describe, and give the origin and significance of the three

types of epithelial cells found in urine sediment.11.Discuss the significance of oval fat bodies.

Learning Objectives Learning Objectives (cont’d)(cont’d)


12. Describe the process of cast formation.13. Describe and discuss the significance of hyaline, RBC, WBC,

bacterial, epithelial cell, granular, waxy, fatty, and broad casts.14. List and identify the normal crystals found in acidic urine.15. List and identify the normal crystals found in alkaline urine.16. Describe and state the significance of cystine, cholesterol, leucine,

tyrosine, bilirubin, sulfonamide, radiographic dye, and ampicillin crystals.

17. Differentiate between actual sediment constituents and artifacts.18. Correlate physical and chemical urinalysis results with microscopic

observations and recognize discrepancies.

Learning Objectives Learning Objectives (cont’d)(cont’d)


• Microscopic examination of the urinary sediment• Identification of insoluble substances (formed elements)

– Red blood cells (RBCs)– White blood cells (WBCs)– Epithelial cells– Casts– Bacteria– Yeast– Parasites – Mucus– Spermatozoa– Crystals– Artifacts

• Least standardized, most time consuming

IntroductionIntroduction


• Microscopic is performed based on physical and chemical results

• Color, clarity, blood, protein, nitrite, leukocyte esterase, and possibly glucose

• Special populations: pregnant women; pediatric, geriatric, diabetic, immunocompromised, and renal patients

Macroscopic ScreeningMacroscopic Screening


• Requested by the physician• Laboratory-specified population• Any abnormal physical or chemical result

Clinical and Laboratory Standards Clinical and Laboratory Standards Institute (CLSI)Institute (CLSI)


• Examine when fresh or preserved– RBCs, WBCs, casts disintegrate in dilute, alkaline urine

• Refrigeration precipitates crystals– Can obscure other elements

• Less contamination (epithelial cells) from a midstream clean-catch specimen

• Thoroughly mix specimen before decanting to the centrifuge tube

Specimen PreparationSpecimen Preparation


• Centrifuge 10 to 15 mL urine (reagent strips fit into 12 mL)

• Quantities <12 mL should be documented• Too little volume = fewer formed elements• Some laboratories correct for volume

Specimen VolumeSpecimen Volume


• Standardize speed and time of centrifugation• 5 min at relative centrifugal force (RCF) of 400 is

ideal• RCF corrects for variations in the diameter of

centrifuge heads; revolutions per minute does not• RCF = 1.118 × 10−5 × radius in centimeters × RPM2

• Do not brake the centrifuge• Cap all specimens

CentrifugationCentrifugation


• Preparation of sediment• Volume of sediment examined

– 0.5 to 1.0 mL• Methods of visualization• Reporting of results• Commercial systems: KOVA

– Calibrated centrifuge tubes, special slides to control volume, decanting pipettes, grids for better quantitation

Sediment StandardizationSediment Standardization


• 0.5 to 1.0 mL after decantation• Concentration factor: volume of urine

centrifuged/sediment volume– Probability of detecting low quantities of formed

elements• Aspirate rather than pour off urine (pipettes

available for this)• Mix sediment gently, not vigorously

Postcentrifuge SedimentPostcentrifuge Sediment


• Be consistent• Commercial systems control this• Glass slide method

– 20 μL– 22 × 22 glass cover slip– Do not overflow cover slip

• Heavier elements (casts) flow outside

Volume of Sediment ExaminedVolume of Sediment Examined


• Chambers capable of containing a standardized– Chamber volume– Size of the viewing area– Approximate number of low-power and high-power viewing

areas

• Based on the area of the field of view using a standard microscope

• CLSI recommends these systems together with standardization of all phases of the methodology

Commercial SystemsCommercial Systems


• Capped, calibrated centrifuge tubes• Decanting pipettes to control sediment volume• Slides that

– Control the amount of sediment examined– Produce a consistent monolayer of sediment for

examination– Provide calibrated grids for more consistent

quantitation

Commercial Systems Commercial Systems (cont’d)(cont’d)


• Be consistent• Minimum 10 low (10×) and 10 high (40×) fields• Low power: casts, general composition

– Scan edges for casts with glass slide method• High power: identification of type• Initial focusing: low power, reduced light

– Focus on epithelial cell, not artifacts that are in a different plane

• Use fine adjustment continuously for best view

Examination of SedimentExamination of Sediment


• Consistent within laboratory• Casts: average per lpf• RBCs, WBCs: average per hpf• Epithelial cells, crystals, etc., in semiquantitative terms

– Few, moderate, many– 1+, 2+, 3+, 4+– Follwed by /lpf or /hpf

Reporting the Microscopic Reporting the Microscopic ExaminationExamination


Converting the average number of elements per lpf or hpf to elements per mL

1. Calculating the area of an lpf or hpf for the microscope in use using the manufacturer-supplied field of view diameter and the formula πr2 = area

Diameter of hpf = 0.35 mm3.14 × 0.1752 = 0.096 mm2

2. Calculating the maximum number of lpfs or hpfs in the viewing area; area under a 22 mm × 22 mm cover slip = 484 mm2

484 = 5040 hpfs .096

Reporting the Microscopic Reporting the Microscopic Examination (cont'd)Examination (cont'd)


3. Calculating the number of hpfs per milliliter of urine tested using the concentration factor and the volume of sediment examined

5040____ = 5040 = 21,000 hpf/mL of urine0.02 mL x 12 .24 4. Calculating the number of formed elements per milliliter of urine by multiplying

the number of hpfs per milliliter by the average number of formed elements per field

4 WBC/hpf × 21,000 = 84,000 WBC/mL

Reporting the Microscopic Reporting the Microscopic Examination (cont'd)Examination (cont'd)


Microscopic Elements

Physical Chemical Exceptions

RBCs TurbidityRed color

+ Blood+ Protein

NumberHemolysis

WBCs Turbidity + Protein Number + Nitrite Lysis + LE Epithelial cells Turbidity NumberCasts + Protein NumberBacteria Turbidity pH Number and type + Nitrite + Leukocytes Crystals Turbidity pH Number and type

Color + Bilirubin

Correlating ResultsCorrelating Results


• Sediment appearance– Cells and casts in various stages of development and

degeneration– Distortion of cells and crystals by the chemical content of the

specimen– The presence of inclusions in cells and casts– Contamination by artifacts

Sediment Examination Sediment Examination TechniquesTechniques


• Low refractive index elements are often difficult to see under bright-field microscopy

• Sternheimer-Malbin stain: crystal violet /Safranin O – Increases refractive index– Stains nuclei, cytoplasm, inclusions– Sedi-Stain, KOVA stain, etc.

• 0.5% solution of toluidine blue enhancement of nuclear detail

• Acetic acid will enhance WBC nuclei– RBCs are lysed by this

Sediment StainsSediment Stains


• Lipid stains– Oil Red O and Sudan III for triglycerides and neutral fats;

cholesterol polarizes• Gram stain

– Identification of bacterial casts• Hansel stain

– Urinary eosinophils– Methylene blue and eosin Y: better than Wright stain

• Prussian blue stain– Hemosiderin granules seen with hemoglobinuria

Sediment Stains Sediment Stains (cont’d)(cont’d)


• Cytodiagnostic urine testing is frequently performed to detect and monitor renal disease/malignancies

• Preparation of permanent slides using cytocentrifugation

• Papanicolaou stain– Transplant rejection– Viral, fungal, and parasitic infections– Cellular inclusions– Pathologic casts– Inflammatory conditions

Cytodiagnostic Urine TestingCytodiagnostic Urine Testing


• Bright field most common in urinalysis– Reduced light is essential– Magnification is 10× and 40×– Par focal means minimal adjustment when changing

objectives (use fine adjustment)– Lower light using the rheostat– Condenser can be raised up and down– Do not use the aperture diaphragm

• Others include phase contrast, polarizing, dark field, fluorescence, and interference contrast

MicroscopyMicroscopy


• Phase-contrast microscopy– Increases refractive index

• Polarizing microscopy– Crystals and lipids– Ability to split light into two beams– Crystals are multicolored– Cholesterol produces Maltese cross formations

• Interference-contrast microscopy– Three-dimensional images

Microscopy Microscopy (cont’d)(cont’d)


• Compound bright-field microscope • Two-lens system

– In the oculars, the objectives– The coarse- and fine-adjustment knobs

• Illumination system– Light source, condenser, and field and iris diaphragms

• Body consisting of– Base– Body tube– Nosepiece

• Mechanical stage

The MicroscopeThe Microscope


The Microscope The Microscope (cont’d)(cont’d)


• Binocular 10×– Adjusts for interpupillary distance

• Field of view is determined by the eyepiece and is the diameter of the circle of view when looking through the oculars

• Objectives: near specimen– UA sediment magnifications of 10× (low power, dry), 40× (high

power, dry)• Final magnification of an object is the product of the

objective magnification times the ocular magnification



• Objective characteristics – Type of objective, magnification, numerical aperture,

microscope tube length, and cover-slip thickness to be used– Length of the objectives attached to the nosepiece varies with

magnification – Changing the distance between the lens and the slide when

they are rotated

• Parfocal– Only minimum adjustment when switching among objectives



• The distance between the slide and the objective is controlled by the coarse and fine focusing knobs– Coarse focus: initial focusing– Fine focus: sharpen image, focusing after changing

magnification



• Illumination– Base– Equipped with rheostat– Regulates intensity– Filters vary illumination and wavelength– Diaphragm contained in the light source controls the diameter

of the light beam– Condenser located below the stage to focus the light– All have adjustments for optimal lighting



• Köhler illumination: provide optimal viewing of the illuminated field



1. Carry microscope with two hands, supporting the base with one hand.

2. Always hold the microscope in a vertical position.3. Only clean optical surfaces with a good quality lens tissue and

commercial lens cleaner.4. Do not use the 10× and 40× objectives with oil.5. Clean the oil immersion lens after use.6. Always remove slides with the low-power objective raised.7. Store the microscope with the low-power objective in position

and the stage centered.

Care of the Microscope Care of the Microscope


• Small amounts of constituents can be normal or pathogenic based on the clinical picture

• Many urines have just a rare epithelial cell• Some constituents are easily distorted

– Concentrations, pH, and presence of metabolites

• Normals are not clearly defined

Urine Sediment ConstituentsUrine Sediment Constituents


RBCsRBCs

• Identification difficulties– Yeast: look for buds– Oil droplets: refractility– Air bubbles: refractility

and possibly in a different plane

– Starch: refractile, polarizes– Reagent strip correlation


RBCs RBCs (cont’d)(cont’d)

• Smooth, nonnucleated, biconcave disks ~7 µm

• Crenated in hypersthenuric urine

• Ghost cells in hyposthenuric urine

• Identify using high power



Air Bubble Oil Droplets


• Dysmorphic RBCs– Glomerular bleeding– Strenuous exercise– Acanthocytic, blebs– Fragmented, hypochromic– Aid in diagnosis



• Normal value: 0–3 to 5/hpf• Damage to glomerular membrane or vascular

injury to the genitourinary tract• Number of cells = extent of damage• Macroscopic versus microscopic hematuria

– Cloudy, red urine, advanced disease, trauma, acute infection, coagulation disorders

– Clear urine, early glomerular disease, malignancy, strenuous exercise, renal calculi confirmation

Clinical SignificanceClinical Significance


WBCsWBCs

• 12 µm• Neutrophil is

predominant• Identify under high power• Glitter cells

– Hypotonic urine– Brownian movement– Swell; granules sparkle– Pale blue if stained– Nonpathologic


WBCs WBCs (cont’d)(cont’d)

• Glitter cell



• Eosinophils– Drug-induced interstitial

nephritis– Renal transplant rejection

• Hansel stain– Percent per 100 to 500 cells– >1% significant– Concentrate sediment,

centrifuge, or cytocentrifuge



• Mononuclear cells– Lymphocytes, monocytes,

macrophages, histiocytes are rare

– Differentiate from renal tubular epithelial (RTE) cells

• Staining– Lymphocytes may resemble

RBCs; seen in early transplant rejection

– May need to refer to cytodiagnostic testing


• Normal = <5 per hpf, more in females• May enter through glomerulus or trauma but also by

amoeboid migration• Increased WBCs = pyuria• Infections: cystitis, pyelonephritis, prostatitis,

urethritis• Glomerulonephritis, lupus erythematosus,

interstitial nephritis, tumors• Report presence of bacteria



Epithelial CellsEpithelial Cells

• Three types1. Squamous2. Transitional (urothelial)3. RTE

• Classification– Squamous: vagina, male

and female urethra– First structures observed– Transitional: bladder, renal

pelvis, calyces, ureters, upper male urethra

– RTE: renal tubules


Squamous Epithelial CellsSquamous Epithelial Cells

• Largest cell in urine• Good for focusing

microscope• Rare, few, moderate,

many• lpf or hpf per laboratory• Normal sloughing• Contamination if not

midstream clean-catch


Squamous Epithelial Cells Squamous Epithelial Cells (cont’d)(cont’d)


• Squamous cell with pathologic significance• Gardnerella vaginalis: vaginal infection• Coccobacillus sp. covers most of the cell and

extends over the edges• Seen in urine but more common in vaginal wet

preparation

Clue CellsClue Cells


• Three forms1. Spherical: absorb water in bladder and become large and

round2. Caudate: appear to have a tail3. Polyhedral: multiple sides

• Differentiate from RTE– Centrally located nucleus

• Syncytia = clumps– Catheterization– Malignancy

Transitional EpithelialTransitional Epithelial(Urothelial) Cells(Urothelial) Cells


Transitional EpithelialTransitional Epithelial(Urothelial) Cells (cont'd)(Urothelial) Cells (cont'd)


• Size and shape vary with renal tubular area• Columnar = proximal convoluted tubule (PCT)• Round, oval = distal convoluted tubule (DCT)• Cuboidal = collecting duct• Three or more cuboidal cells = renal fragment

Renal Tubular Epithelial CellsRenal Tubular Epithelial Cells


PCT CellsPCT Cells

• Larger than other RTEs• Columnar, convoluted,

rectangular• May resemble casts• Coarsely granular

cytoplasm• Notice presence of

nucleus


DCT CellsDCT Cells

• Round or oval shaped, smaller

• May resemble WBCs or spherical transitional cells

• Observe the eccentrically placed nucleus to differentiate from spherical transitional


Collecting Duct RTEsCollecting Duct RTEs

• Cuboidal, never round– At least one straight

edge– Eccentric nucleus

• Three or more cells in clump is renal fragment; often large sheets

• PCT and DCT not seen in clumps


• RTE cells are the most clinically significant urine epithelial cells; indicate tubular necrosis; fragments indicate severe destruction– Heavy metals, drug toxicity, hemoglobin, myoglobin,

viral infections, pyelonephritis, transplant rejection, salicylate poisoning

• Single cuboidal cells = salicylate poisoning• Absorb: bilirubin, hemoglobin, lipids• Hemosiderin stains with Prussian blue



RTE cellsRTE cells


Oval Fat BodiesOval Fat Bodies

• RTE cells that have absorbed lipid in the filtrate

• Also free-floating refractile droplets

• Maltese cross formation with polarized light

• If negative check with Sudan III or oil red O stain


Oval Fat Bodies Oval Fat Bodies (cont’d)(cont’d)

• Stain polarizing negative structures

• Cholesterol polarizes• Triglycerides and neutral

fats stain• Lipiduria: nephrotic

syndrome, acute tubular necrosis, diabetes, crush syndromes


BacteriaBacteria

• Urine is usually sterile, contaminated on the way out; contaminants multiply fast

• WBCs should accompany bacteria in UTI

• Report few, moderate, many per hpf

• Rods and cocci may be seen; rods most common

• Nitrite helps to confirm rods, not cocci


• Single, refractile, budding structures• Mycelial forms may be present• Report: few, moderate, many• Diabetic urine: ↑ glucose and acid ideal for yeast

growth• Immunocompromised, vaginal moniliasis• Nitrite negative, WBCs present• Confuse with RBCs

YeastYeast


Yeast Yeast (cont’d)(cont’d)


• Most common: Trichomonas vaginalis– Pear-shaped flagellate– Swims across field rapidly

• Report few, moderate, many• If not moving, may resemble WBC, transitional,

or RTE cells• Also Schistosoma haematobium and Enterobius

vermicularis

ParasitesParasites


Parasites Parasites (cont’d)(cont’d)


SpermatozoaSpermatozoa

• Oval, tapered heads and long tail• Urine is toxic to sperm, so they

are immobile • Rarely significant, infertility:

sperm expelled into bladder instead of urethra

• May cause positive protein• Reporting varies with

laboratories• Lack of clinical significance, legal

consequences


MucusMucus

• Protein from RTE, glands, squamous cells

• Threadlike, low refractive index

• Confuse with casts– Irregular, composed of

uromodulin protein• Female specimens, no

clinical significance


• Elements unique to the kidney• Formed in DCT and collecting duct• Parallel sides, rounded ends, inclusions• Detect under low power, ID high power• Scan edges of glass cover slip• Low light is essential• Report number per lpf• Many pathologic and nonpathologic causes

CastsCasts


• Uromodulin protein secreted by RTE of DCT and collecting duct

• Consistent excretion normally– ↑ stress and exercise

• Formation of protein fibrils into matrix– Urine stasis, acid pH, Na, and Ca

• Uromodulin protein not detected by reagent strips• ↑ protein is from renal disease

Composition and FormationComposition and Formation


• Formation– Aggregated uromodulin fibrils attached to RTEs– Interweaving to loose network, traps elements– More interweaving to form solid matrix– Attachment of elements to matrix– Detachment of fibrils from RTEs– Excretion of cast

• Cylindroids– Tapered ends, one or both– Same significance as cast

Composition and Formation Composition and Formation (cont’d)(cont’d)


Hyaline CastsHyaline Casts

• Low refractive index• Colorless when unstained• Uromodulin protein• Use low light or phase• Normal parallel sides or

convoluted, wrinkled, cylindroid, occasional adhering cell or granule



• Most frequently seen• 0 to 2 is normal• Nonpathologic: stress,

exercise, fever, heat exposure, dehydration

• Pathologic: glomerulonephritis, pyelonephritis, chronic renal disease, congestive heart failure


Clinical Significance Clinical Significance (cont’d)(cont’d)


RBC CastsRBC Casts

• Orange-red color• Embedded and

adhering cells• May be fragmented• Confirm seeing free

RBCs and positive reagent strip for blood

• Look for cast matrix to avoid mistaking a RBC clump for a cast


• Bleeding within the nephron, casts are more specific than free RBCs in urine

• Glomerular damage or nephron capillary damage• Glomerular damage: dysmorphic RBCs and

elevated protein• May be seen following strenuous exercise



Clinical Significance Clinical Significance (cont’d)(cont’d)

• Cells begin to disintegrate with more stasis of urine flow

• Hemoglobin and myoglobin damage tubules

• Hemoglobin degraded to methemoglobin = dirty brown casts

• Look for RTE cells to confirm tubular necrosis


WBC CastsWBC Casts

• Mostly neutrophils and lobed nucleus and granules are seen

• Staining helps differentiate from RTE cells

• May be tightly packed; look for cast matrix to distinguish from WBC clump


WBC Casts WBC Casts (cont’d)(cont’d)

• WBC casts are seen with infection and inflammation of the tubules

• Pyelonephritis: WBC casts, bacteria

• Acute interstitial nephtitis: WBC casts, no bacteria

• May accompany RBC casts


• May be pure bacteria or mixed with WBCs• Resemble granular casts• Look for free WBCs and bacteria• Confirm with Gram stain• Seen in pyelonephritis• Mixed cellular casts

– Glomerular nephritis: RBCs and WBCs• Look for predominant type of cell

Bacterial CastsBacterial Casts


Epithelial (RTE) CastsEpithelial (RTE) Casts

• Formed in DCT = small, round cells

• Fibrils forming cast pull cells from damaged tubules

• Majority of cells are on the cast matrix

• Differentiate from WBCs: stain to show single nucleus



• Tubular damage, heavy metals, viral infections, drug toxicity, graft rejection, pyelonephritis

• Cells may appear bilirubin stained

• Look for matrix to distinguish fragments


Fatty CastsFatty Casts

• Seen with oval fat bodies (OFBs) and fat droplets

• Highly refractile, OFBs may attach to matrix

• Polarized microscopy and lipid stains

• Nephrotic syndrome, diabetes, crush trauma, tubular necrosis


• RBC and WBC casts in glomerulonephritis • WBC and RTE cell casts, or WBC and bacterial

casts in pyelonephritis• Identification difficult

– Staining or phase microscopy aids in the identification

Mixed Cellular CastsMixed Cellular Casts


Granular CastsGranular Casts

• Coarse and finely granular

• Granule origin– RTE lysosomes, excreted

in normal metabolism, more after exercise and activity

– Disintegration of cellular casts and free cells


Granular Casts Granular Casts (cont’d)(cont’d)

• Detect with low power, ID with high power

• Granules disintegrate to form waxy casts

• Differentiate granular casts from clumps of debris and crystals; look for matrix


Waxy CastsWaxy Casts

• Brittle, highly refractile• Often fragmented with

jagged ends and notches• Well visualized with stain• Degenerated hyaline and

granular casts• Extreme urine stasis• Renal failure


Broad CastsBroad Casts

• Renal failure casts• Destruction and widening of

the DCTs• Formation in the upper

collecting duct• All types of casts may be

broad• Most common are granular

and waxy• Bilirubin stained from viral

hepatitis


• Most are not clinically significant but are reported• True geometrically formed structures or as amorphous

material• Must differentiate from the few abnormal crystals

indicating liver disease, inborn errors of metabolism, and damage to tubules

• Iatrogenic: caused by medications or treatments• Report: rare few, moderate, many

Urinary CrystalsUrinary Crystals


• Precipitation of urine solutes: salts, organic compounds, and medications

• Formation based on temperature, solute concentration, and pH

• Many crystals in refrigerated specimens• High specific gravity needed in fresh specimens

Crystal FormationCrystal Formation


• Most have characteristic shapes and colors• Most valuable ID is urine pH• Classification: normal acid, normal alkaline • All abnormal crystals are found in acid urine• Polarized microscopy characteristics are valuable

in ID

General Identification TechniquesGeneral Identification Techniques


• Temperature and pH contribute to formation and solubility

• Amorphous urates form in refrigerated acid urine; will dissolve with heat

• Amorphous phosphates form in refrigerated alkaline urine; will dissolve in acetic acid; so will RBCs

Solubility CharacteristicsSolubility Characteristics


Normal Crystals in Acid UrineNormal Crystals in Acid Urine

• Amorphous urates– Yellow-brown granules

microscopically– Urine sediment has pink

color due to the pigment uroerythrin attaching on surface of granules

– Often in clumps; may resemble casts

– pH usually greater than 5.5


Uric Acid CrystalsUric Acid Crystals

• Rhombic, whetstones, wedges, rosettes

• Yellow-brown color• May resemble cystine

crystals but always polarize

• ↑ purines, nucleic acids• Chemotherapy for

leukemia, gout


Calcium Oxalate CrystalsCalcium Oxalate Crystals

• Acid and neutral pH• Dihydrate is envelope or

two pyramid–shaped– Most common

• Monohydrate is oval or dumbbell shaped– Antifreeze poisoning

• Calcium oxalate is a major component of renal calculi


Amorphous PhosphatesAmorphous Phosphates

• May appear similar to amorphous urates

• Differentiate– Alkaline pH and heavy

white precipitate after refrigeration


Normal Crystals in Alkaline UrineNormal Crystals in Alkaline Urine

• Triple phosphate• Colorless, prism, or coffin-

lid shaped• Highly alkaline urine and

urinary tract infections (UTIs)

• Polarize• No clinical significance


Calcium Phosphate and CarbonateCalcium Phosphate and Carbonate

• Phosphate– Flat rectangles and thin

prisms in rosettes– No clinical significance

• Carbonate– Small, dumbbell, and

spherical shapes– Gas produced with

addition of acetic acid– No clinical significance


Ammonium Biurate CrystalsAmmonium Biurate Crystals

• Yellow-brown, spicule-covered spheres; “thorny apples”

• Only urates in alkaline urine

• Old specimens and with urea-splitting bacteria


Abnormal Crystals Abnormal Crystals

• Cystine crystals– Hexagonal, thin and thick

plates– Similar to uric acid– UA polarizes but only thick

cystine crystals polarize– Seen in cystinuria: inability

to reabsorb cystine– Confirm: cyanide

nitroprusside


Cholesterol CrystalsCholesterol Crystals

• Refrigerated specimens• Rectangular plates with

characteristic notched corners

• Highly birefringent• Nephrotic syndrome

accompanying fatty casts and OFBs


• Radiographic dye– Similar to cholesterol crystals, polarize– Patient history– Very high SG with refractometer

Radiographic Dye CrystalsRadiographic Dye Crystals


Liver Disease CrystalsLiver Disease Crystals

• Tyrosine crystals– Fine yellow needles in

clumps or rosettes– Seen with leucine

crystals– Inherited amino acid

disorders• Leucine crystals

– Yellow-brown spheres with concentric circles and radial striations


Liver Disease Crystals Liver Disease Crystals (cont’d)(cont’d)

• Bilirubin crystals– Clumped needles or

granules– Characteristic yellow

color– Viral hepatitis with

tubular damage– Positive reagent strip for

bilirubin


Sulfonamide CrystalsSulfonamide Crystals

• Possibility of tubular damage if crystals are forming in the nephron

• Shapes most frequently encountered include needles, rhombics, whetstones, sheaves of wheat, and rosettes with colors ranging from colorless to yellow-brown


Ampicillin CrystalsAmpicillin Crystals

• Ampicillin crystals appear as colorless needles that tend to form bundles following refrigeration


Urinary Sediment ArtifactsUrinary Sediment Artifacts

• Material fibers, meat and vegetable fibers, and hair

• Starch, oil droplets, air bubbles, pollen grains, vegetable fiber, hair, diaper fiber


Urinary Sediment Artifacts Urinary Sediment Artifacts (cont’d)(cont’d)

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Copyright © 2014. F.A. Davis Company CHAPTER 6 MICROSCOPIC EXAMINATION OF URINE