Urine crystal

Descriptions of urine sediment

1. Hyaline Cast
Hyaline casts are formed in the absence of cells in the
tubular lumen. They have a smooth hyaline cast texture
and a refractive index very close to that of the
surrounding fluid. Reduced lighting is essential to see
hyaline casts.
Increased in acute glomerulonephritis, pyelonephritis,
chronic renal disease and congestive heart failure.

RBC Cast
Red blood cell casts are hyaline casts containing
erythrocytes and are usually orange to red in color.
These casts are filled with intact erythrocytes, and one
can readily distinguish the typical spherical shape of the
cells as well as the distinct cell margins. Many red blood
cells must be present in the matrix to call the structure a
red blood cell cast.
Associated with glomerular damage
(Glomerulonephritis).

WBC Cast
These casts are generally the same size and shape as
hyaline casts, and are basically hyaline casts filled with
leukocytes. An occasional white blood cell occurring
within a cast has no serious implications; it is only when
the casts are nearly or completely packed with
leukocytes that they are designated as white blood cell
casts.
White blood cell casts are a sign of intrinsic renal
disease and are seen in suppurative diseases such as
pyelonephritis and inflammatory conditions such as
glomerulonephritis.

Epithelial Cell Cast
When epithelial cells are sloughed off from the tubules,
they tend to coalesce (grow together) and subsequently
adhere to or become incorporated within a protein
matrix. Such a structure is called an epithelial cell cast.
These casts are usually swollen and tinged with a yellow
or brown color. Epithelial cell casts can signify aseptic
degeneration of the renal tubules.

Fatty Cast
The breakdown of the epithelial lining of the tubules
may produce fat droplets instead of granules. These fat
droplets are incorporated into the cast matrix to produce
a fatty cast. Fatty casts are quite similar to waxy casts in
appearance. However, the inclusion of the relatively
large fat droplets makes them more refractile than either
granular or waxy casts; they are lighter in color than
waxy casts.
Fatty casts are usually seen in degenerative tubular
disease, associated with tubular deposition of fat and
lipoid material.

Granular Cast
Granular casts are about the same size as hyaline casts
and are composed of common hyaline material in which
numerous granules are embedded. This granular material
consists of protein, disintegrated leukocytes or
erythrocytes, fats, and degenerated epithelial cells.

Waxy Cast
Waxy casts, like hyaline casts, are homogenous.
However, they are more opaque than hyaline casts and
are a waxy yellow in color, resembling a structure made
from paraffin. They tend to be short and broad with
irregular broken ends. They can be distinguished from
hyaline casts by a higher refractive index. Their size
varies, and, at times, they may be extremely large and
irregular. Waxy casts are considered to have remained in
the tubules for a long time and represent the final stage
in the deterioration of granular casts. They are indicative
of localized oliguria or anuria and occur in cases of
severe chronic renal disease.

Amorphous Urates
Often appear in noncrystalline amorphous form. Have
yellowish-brown (pinkish) granular appearance.
In urine with uric acid in it, amorphous urates will
precipitate out of solution upon refrigeration. They
appear as a heavy pink sediment and impart a cloudy to
turbid appearance of the mixed urine.

Uric Acid
Uric acid crystals can vary in both size and shape, as can
be seen in the slide above. They can look like barrels,
rosettes, rhomboids, needles or hexagonal plates. They
are usually amber in color, irrespective of the size or
shape of the individual crystal.

Calcium Oxalate (Dihydrate)
Calcium oxalate dihydrate crystals appear as colorless
bipyramids of various sizes (“envelope form”).
They can be seen in normal individuals with high dietary
oxalate ingestion, in patients with nephrolithiasis, and in
patients with acute renal failure due to ethylene glycol
ingestion.

2. Calcium Oxalate (Monohydrate)
Calcium oxalate monohydrate crystals are colorless and
can assume several shapes, including ovoids, biconcave
disks, rods and dumbbells.
This form of crystals is seen ethylene glycol poisoning.

Amorphous Phosphate
Similar to amorphous urates except usually colorless. In
urine with phosphate in it, amorphous phosphates will
precipitate out of solution upon refrigeration. They
appear as a heavy white sediment and impart a cloudy to
turbid appearance of the mixed urine.’

Calcium Phosphate
Large flat-shaped plates or wedge-shaped prisms. The
prisms often appear in rosettes. Single prisms are usually
blunt on one end and pointed on the other end.
Although considered normal they may also be associated
with kidney stone formation.

Triple Phosphate
Typically appear in "coffin-lid" form. May also appear
as "fern-leaf" shape if freshly formed.
Although considered normal they may also be associated
with kidney stone formation

Ammonium Biurate
Yellowish-brown, can be seen in a "thorn apple" shape
(round with thorny projections) or in spherical form.
Ammonium biruate crystals can be seen in normal urine.
However, the presence of ammonium biurate crystals
especially in combination with a urine pH 9.0 or higher
usually indicates an old or poorly preserved specimen.
Best practice is to NOT report any urinalysis results on
the sample as it has been compromised. A recollect
should be requested.

Calcium Carbonate
Appearance: Small, colorless granules or dumbbells.
Not clinically significant but can be confused with other
elements. A unique feature of calcium carbonate is that
the crystals effervesce with hydrochloric acid or acetic
acid. This can help to confirm the presence of calcium
carbonate in the urine.

Cystine
Appearance: Colorless, thin, hexagonal plates
Cystine crystals are found in the inherited condition,
cystinuria. Cystine crystals are the most frequent cause
of kidney stones in children.
The presence of cystine crystals should be confirmed by
cyanide-nitroprusside test (turns red-purple).

Cholesterol
Appearance: clear, flat plates with notched corners.
The appearance of cholesterol is associated with the
Nephrotic Syndrome.
Cholesterol crystals are accompanied by a positive
biochemical test for protein. They usually appear after
the urine sample has been refrigerated and may be
accompanied by oval fat bodies, fatty casts, and free fat
droplets in the sediment.

Leucine
Appearance: yellow-brown spheroids with concentric
rings around the outer edge and radial striations in the
center.
Leucine crystals may be seen in liver disorders in which
amino acid metabolism is impaired.
The presence of leucine crystals is often accompanied by
a positive biochemical test for bilirubin and is often
accompanied by tyrosine crystals in the same sediment.

Tyrosine
Appearance: colorless to yellow-brown single needles.
Also seen as sheaves or rosettes.
Tyrosine crystals may be seen in tyrosinemia and in
certain liver disorders in which amino acid metabolism
is impaired.
The presence of tyrosine crystals is usually accompanied
by a positive biochemical test for bilirubin and are often
accompanied by the presence of leucine crystals in the
sediment.

Bilirubin
Appearance: Yellow-brown needles or granules. They
are frequently attached to the surface of cells.
Bilirubin crystals are seen in several hepatic disorders.
The appearance of bilirubin crystals should be
accompanied by a positive biochemical test for bilirubin
(reagent test pad and Ictotest).

3. Sulfonamides
Appearance: flat needles, sheaves of small needles or as
spheroids. Often brown in color.
The presence of sulfanomide crystals usually indicates
administration of the drug and not necessarily a
pathological condition. However, their presence is also
associated with kidney stone formation.

Radiographic Dyes
Appearance: flat needles or sheaves accompanied by
round globules but are variable in form.
When the presence of radiopaque dye crystals is
suspected, the ordering location should be consulted to
confirm administration of contrast media.
The presence of these crystals in the urine is associated
with very high specfic gravity results by refractometry
(>1.035). Specific gravity by the reagent test pad
method is not affected by the presence of these crystals.

Ampicillin
Ampicillin crystal appear as colorless needles that tend
to form bundles following refrigeration.
These crystals are present in urine due to massive doses
of penicillin compounds without adequate hydration.

Starch
Starch granule contamination may occur when
cornstarch is the powder used in powdered gloves. The
granules are highly refractile spheres, usually with a
dimpled center. They resemble fat droplets when
polarized, producing a maltese cross formation.

Oil Droplets
Highly refractile and may resemble RBCs. Oil droplets
may result from contamination by immersion oil or
lotions and creamsand may be seen with fecal
contamination.

Air Bubbles
Air bubbles are also highly refractile. It occurs when the
specimen is placed under a coverslip.

Pollen Grains
Seasonal contaminants that appear as spheres with a cell
wall and occasional concentric circles.
Fiber
Cotton, plant, and paper fibers maybe confused for
urinary casts. Care in sample collection and handling
will minimize the presence of such material.