Microscopic Examination of Urine

Question 1

Hyaline cast

Answer 1

Colorless, varied morphology
Follow exercise, dehydration, heat, and emotional stress
Disease: Acute glomerulonephritis, pyelonephritis, chronic renal disease, CHF

Question 2

RBC cast

Answer 2

Orange/red, hemoglobin and intact RBCs
Seen after strenuous contact sports
Disease: bleeding in nephron, damage to glomerulus/renal capillaries (poststreptococcal infections)

Question 3

WBC cast

Answer 3

Contains neutrophils

Disease: Infection (pyelonephritis) or inflammation in nephron (acute interstitial nephritis)

Question 4

Bacterial cast

Answer 4

Bacilli contained in cast or bound to surface, can contain WBCs
Disease: pyelonephritis

Question 5

Epithelial cell cast

Answer 5

Contain renal tubular epithelial cells

Disease: advanced renal tubular damage (heavy metal/chemical/drug toxicity, viral infections, allograft rejection)

Question 6

Granular cast

Answer 6

Coarsely or finely granular
Seen with hyaline casts following stress and exercise \
Disease: degeneration of cellular cast due to slowing of urine flow (cast kept in tubule for longer)

Question 7

Waxy cast

Answer 7

High refractive index, smooth, cracks or fissures on sides

Disease: chronic renal failure with significant urine stasis

Question 8

Fatty cast

Answer 8

Highly refractile, yellow-brown fat droplets

Disease: nephrotic syndrome, toxic tubular necrosis, diabetes mellitus

Question 9

Broad cast

Answer 9

All types of casts can occur in broad form, most common are granular and waxy
Disease: renal failure (form due to anuria)

Question 10

Amorphous urates

Answer 10

Not clinically significant

Small yellow/brown granules, more seen in refrigerated samples, dissolve at alkaline pH or heat above 60 C

Question 11

Uric acid crystals

Answer 11

Seen in gout, chemotherapy, and Lesch-Nyhan syndrome
Yellow to orange/brown, can be colorless
Pelomorphic, four-sided flat plates, rhombic plates, wedges, and rosettes

Question 12

Calcium oxalate crystals

Answer 12

Found in foods, also metabolite of ascorbic acid
Colorless, appears as octahedral envelope, 2 pyramids joined at base, or dumbbell/oval shape
Associated with renal calculi formation, seen in kids after ingesting ethylene glycol

Question 13

Bilirubin crystals

Answer 13

Fine needles/granules, yellow to brown

Liver disease, viral hepatitis

Question 14

Tyrosine crystals

Answer 14

Fine needles, colorless to yellow, clumps or rosettes
Severe liver disease, inherited diseases that affect amino acid metabolism
May be seen with leucine crystals in urine that tests positive for bilirubin

Question 15

Leucine crystals

Answer 15

Yellow to brown, oily looking spheres

Severe liver disease and inherited diseases that affect amino acid metabolism

Question 16

Cystine crystals

Answer 16

Colorless, hexagonal plates\
Congenital disorder that inhibits renal tubular reabsorption of cystine
Associated with renal calculi formation

Question 17

Cholesterol crystals

Answer 17

Clear, flat, rectangular plates with notch in one or more corners, seen more often after refrigeration
Associated with nephrotic syndrome and other lipidurias

Question 18

Triple phosphate crystals

Answer 18

Colorless, 3 to 6 sides prism, coffin lid

Not clinically significant, may be associated with UTI and prostatitis

Question 19

Calcium phosphate crystals

Answer 19

Colorless, thin prisms or rectangular plates

Not clinically significant, may be associated with renal calculi formation

Question 20

Ammonium biurate crystal

Answer 20

Normal crystal normally seen in old samples, dissolves at 60 C
Yellow to brown spheres, irregular thorny projections (thorn apple)

Question 21

Calcium carbonate crystals

Answer 21

Small, colorless, dumbbell or spherical

Not clinically significant