Microscopic examination of urine

What crystals are found in acidic urine?

Uric acid, calcium oxalate, cystine, bilirubin

What crystals are found in alkaline urine?

calcium carbonate, triple phosphate, ammonium biurate, calcium phosphate

What crystals are found in alkaline and acidic urine?

cholesterol, leucine, tyrosine, sulfa

What crystals are considered normal?

Uric acid, calcium carbonate, triple phosphate, calcium oxalate, ammonium biurate, calcium phosphate

What crystals are considered abnormal?

cystine, cholesterol, leucine, tyrosine, sulfa, bilirubin

What are the conditions for cast formation?

• high urine acidity

• high urine concentration

• reduced urine flow

How are samples prepped for a microscopic urinalysis?

• 10-15 ml of well-mixed urine

• centrifuge & decant

• well-mixed drop of sediment

Is the oil lens used in microscopic urinalysis?

No, 40x is the max

What is done on 10x?

ID and quantification of casts and mucus. Look at 2-4 edges of coverslip and 10-15 fields in center

What is done on 40x?

Id and quantification of cells, microorganisms and crystals

What are polarizing lenses used for?

• crystals

• lipids

What is the matrix of a cast made out of?

Tamm horsfall protein

What are the only element in urine sediment that are unique to the kidney?

Casts

What is the progression of cast types?

Hyaline → cellular → granular→ waxy casts

What are the two types of granular casts?

• coarse

• fine

What is the most common cast type?

hyaline/cylindroid

What are cellular casts?

• TH protein + cellular element

• any number is abnormal

• associated with bleeding, infection, tubular damage

RBC casts

WBC cast

Granular cast

What are granular casts?

• breakdown of cellular casts

• any number is abnormal

What are waxy casts?

• aged granular casts

• high refractive index

• any number abnormal

Waxy casts

Oval fat bodies

• Renal epithelial cells or macrophages that are filled with fat or lipid droplets

• of cholesterol esters are present will form Maltese cross under polarizing light

Fatty casts

Red blood cells in urine are?

• abnormal in any number

• may be crenated or “ghost” cells

White blood cells in urine?

• 0-5/hpf is normal

• associated with infection and inflammation

Glitter cells are?

WBCs in hypotonic solution, swollen so granules appear to glitter as they move

Squamous epithelial cells are?

• normal

• result of sloughing

Transitional epithelial cells are?

• few present is normal

• from the bladder, renal pelvis and urethra

• central nucleus

Renal epithelial cells are?

• few present in normal

• increased amounts associated with tubular necrosis, renal damage

• most significant epithelial cell

Uric acid crystals

acid urine

Amorphous urates

Only different between amorphous urates and phosphate is the ph

Calcium oxalate

Acid-neutral urine

hippuric acid

rare but insignificant, acid urine

triple phosphate

• alkaline urine

• coffin lid

• may be increased with stone formation

calcium carbonate

alkaline

Ammonium biurate

alkaline

Cystine crystals

• colorless

• hexagonal

• associated with metabolic defect

cholesterol

• colorless

• flat, notched rectangles

• rarely seen

• associated with tissue breakdown and renal disease

Leucine

• yellow-brown spheres

• rare

• associated with severe liver disease

tyrosine

• clumps of needles

• associated with severe liver disease

bilirubin

• granules and clumped needles

• yellow

• associated with liver disease and bilirubinuria

sulfa

• sheaves of needles

• associated with sulfa medications

• can lead to tubular damage

What else can be found in urine?

• bacteria

• yeast

• parasites

• sperm

• mucus

• hemosiderin

When are bacteria usually reported?

when they are cocci

yeast in urine

often confused with RBCs

trichomonas

pin worm

• sign of fecal contamination

mucus

• protein material

• small amount normal

• increased with poor collection and/or inflammation

• easily confused with hyaline casts

Hemosiderin

• not normally found

• yellow-brown granules

• associated with rbc destruction

• confirm with prussian blue

Starch

• frequently found

• must differentiate from significant findings

Oil/bubbles

will not form maltese cross

What are common artefacts in urine?

• starch

• oil/bubbles

• glass fragments

• hairs, pollen, talc, fiber

If the strip test is positive for protein what do we expect to see on the microscope?

• may expect casts, wbcs, 3-4+ mucus

If the strip test is positive for blood what do we expect to see on the microscope?

• RBCs

• if not present:

  • lysis

  • misidentified as yeast

  • myoglobin

If RBCs seen on microscope but reagent strip test was negative?

• consider possible vitamin C interference

• yeast misidentified as RBCs

If the strip test is positive for nitrite what do we expect to see on the microscope?

• bacteria

• if bacteria present but nitrite is negative

  • non nitrate reducers

  • decreased incubation time

  • fully metabolized to nitrogen

If the strip test is positive for LE what do we expect to see on the microscope?

White blood cells

If the ph is acidic what crystal should we see?

• Calcium oxalate

• uric acid

• other abnormal crystals

• amorphous urates

If the ph is alkaline what crystals should we see?

• triple phosphate

• ammonium biurate

• amorphous phosphates

What dye is used to stain triglycerides?

sudan III or oil red O

Calcium phosphate