M4U3: URINARY CRYSTALS AND MISCELLANEOUS ELEMENTS Flashcards
Crystals which are frequently found in acidic urine
uric acid
calcium oxalate
amorphous urates
Crystals not frequently found in urine
calcium sulfate sodium urates hippuric acids cystine leucine tyrosine cholesterol sulfa
factors affecting formation of crystals
urine pH
concentration of solute in urine
flow of urine through the tubules
temperature
Why is microscopic evaluation of urine is important for detection of crystals ?
no or very limited chemical tests detect their presence
___ represent the majority of crystals seen in alkaline urine and include ___, ____, and ___
phosphates
amorphous phosphate
triple phosphate
calcium phosphate
Microscopically, these appear as small, yellow-brown granules much like sand
amorphous urates
Sometimes amorphous urates may appear in clumps and may resemble a formed element
granular casts
___ are frequently encountered in specimens that have been refrigerated and produce a very characteristic pink sediment
amorphous urates
The characteristic pink sediment produced by refrigerated amorphous urates is due to the accumulation of what pigment ?
uroerythrin
Amorphous urates are found in acidic urine in what pH ?
greater than 5.5
This urine crystal appears as small, yellow-brown balls or spheres
acid urates
acid urates are often misidentified as ___
leucine crystals
Acid urates appear as larger granules and may have spicules similar to the ____ crystals seen in alkaline urine
ammonium biurate
Acid urate crystals can be present when the urine pH is ___ but frequently are not observed in fresh urine
neutral to slightly acidic
What urine crystals dissolve at 60C ?
acid urates
monosodium urates
Acid urates can be converted to uric acid crystals by the addition of ____
glacial acetic acid
These are distinct form of a uric acid salt which appears as colourless to light-yellow slender, pencil-like prisms
monosodium urates
These urine crystals are seen in synovial fluid during episodes of gout, and can appear in urine
monosodium urates
____ and ___ are solutes normally found in the urine of healthy individuals
calcium
oxalate
Approximately 50% of the oxalate typically present in urine is derived from ___ or from ____
ascorbic acid (vitamin C) oxalic acid
These foods are high in oxalic acid
vegetables (rhubarb, tomatoes, asparagus, spinach)
These beverages are high in oxalic acid
cocoa
tea
coffee
chocolate
Which form of calcium oxalate less common ?
monohydrate form
This urine crystal is octahedral or pyramidal in shape
dihydrate calcium oxalate
When this urine crystal is viewed from one end, they appear as squares scribed with lined that intersect in the center
dihydrate calcium oxalate
This urine crystal is sometimes called enveloped crystals
dihydrate calcium oxalate
This urine crystal is small and ovoid or dumbbell shaped and can resemble RBCs
monohydrate calcium oxalate
____ crystals may cluster together and can stick to mucous threads. When this occurs, they may be mistaken for crystal casts.
calcium oxalate
What colour is calcium oxalate identified by ?
they are colourless
___ crystals are the most frequently observed crystals in human urine
calcium oxalate
why is calcium oxalate the most frequently observed crystals in human urine ?
can form in urine of any pH
greatly affected by diet
What may cause an increase in numbers of calcium oxalate crystals ?
ingestion of the oxalate precursor ethylene glycol (antifreeze)
during severe chronic renal disease
diabetes mellitus
liver disease
Uric acid crystals are seen in a variety of shapes and these include ? (7)
rhombic or diamond
four-sided flat plates (whetstones/cubes)
barrel
wedges
bands
may cluster together to form rosettes
may also have a six-sided shape, similar to cystine crystals
These urine crystals usually appear yellow to golden brown and the intensity of their colour varies directly with the thickness of the crystal
uric acid crystals
What may be the reason for uric acid appearing colourless ?
thin or when urine is low in uroerythrin
These crystals under polarizing microscopy exhibit a strong birefringence and produce a variety of interference colours
uric acid crystals
Uric acid crystals can be present only if the urine pH is less that ___ and at a pH greater than that is in its ____ form, forming urate crystals
5.7
ionized
Generally, uric acid crystals are 17 times less soluble than _____ crystals
urate salt
Uric acid is a normal urine solute that originates from ___
catabolism of purine nucleosides (adenosine and guanosine from RNA and DNA)
increased amounts of urinary uric acid can be present in these instances
administration of cytotoxic drugs (e.g., chemotherapeutic agent)
gout
patients with Lesch-Nyahn Syndrome
These are non-crystalline form of phosphates that resemble fine, colourless grains of sands in the sediment
amorphous phosphates
These granular particles which are also found in neutral urine have no definite shape and are usually microscopically indistinguishable from amorphous urates
amorphous phosphates
How to differentiate amorphous phosphates and amorphous urates ?
amorphous phosphate:
- large quantity causes urine to appear cloudy
- precipitate/sediment button is white or gray
- soluble in acid
- do not dissolve at approximately 60C
Why is triple phosphate referred to as that ?
ammonium
magnesium
phosphate
materials
It is a colourless crystal that appears both in alkaline and neutral urine with the most common form being three to six-sided prisms with oblique terminal surfaces, described as “coffin lids”
Triple phosphate
With prolonged storage, these crystals can dissolve, taking on a feather form that resembles a fern leaf
triple phosphate
Triple phosphate crystals have been associated with ____ and have been implicated in ___
UTI
formation of renal calculi
This urine crystal is present in any urine pH as dibasic and monobasic
calcium phosphate
calcium phosphate as dibasic is
calcium monohydrogen phosphate
calcium phosphate as monobasic calcium phosphate is
calcium biphosate
dibasic calcium phosphate crystals sometimes called stellar phosphates, appear as ___ (6)
colourless
thin
wedgelike prisms
arranged in small groupings or in a rosette pattern
each prism has one tapered or pointed end, with the other end squared off
others may appear as long needles arranged in bundles or sheaves
Dibasic form of calcium phosphate can be confused with sulfonamide crystals when the urine pH is in the neutral range. How do we differentiate them ?
dibasic forms dissolve in dilute acetic acid while sulfonamides do not
___ crystals appear microscopically as irregular, granular sheets or flat plates that can be large and may be noticed floating on top of a urine specimen
monobasic calcium phosphate
Monobasic calcium phosphate can resemble ___
large degenerating squamous epithelial cells
Both types of calcium phosphate have no clinical significance, though calcium phosphate is a common constituent of ___
renal calculi
These are large, flat, colourless crystals, appearing as elongated rectangular or rhomboid plates. These can be notched and their edges can be irregular or eroded
Magnesium phosphate
What is a characteristic of monobasic calcium phosphate crystals with polarizing microscopy ?
weakly birefringent
What is a characteristic of magnesium phosphate crystals with polarizing microscopy ?
weakly birefringent
These are yellow-brown spherical crystals with striations/projections or spicules on the surface giving them a “thorny apple” appearance
Ammonium biurate
Ammonium biurate occur most frequently in urine specimens that have undergone ____
prolonged storage
Why is ammonium biurate only clinically significantly when they form precipitate in fresh urine specimens
because in vivo precipitation can cause renal tubular damage
What is a characteristic of ammonium biurate crystals with polarizing microscopy ?
strongly birefringent
What are ways to dissolve ammonium biurate ?
acetic acid
heating to 60C
Similar to other urate salts, ammonium biurate can be converted to uric acid crystals with the addition of ___
concentrated HCl or acetic acid
Ammonium biurate can resemble some forms of ___
sulfonamide crystals
These urine crystals are tiny, colourless granular crystals that assume dumbbell, spherical or tetrad shapes and is slightly larger than amorphous material
calcium carbonate
How are calcium carbonate crystals differentiated from amorphous materials ?
formation of gas after the addition of acetic acid
How are calcium carbonate crystals differentiated from bacteria ?
calcium carbonate are birefringent
Abnormal urine crystals are mostly found at what pH ?
acidic
These crystals usually appear yellow-brown small clusters of fine needles, and sometimes in granules and plates and only form in acidic urine
bilirubin
Why are bilirubin classified as abnormal crystals ?
because bilirubinuria indicates a metabolic disease process
These crystals are clear, colourless, hexagonal plates with uneven sides, They are often refractile, laminated or layered and tend to clump.
cystine crystals
What pH can cystine crystals be primarily found at ?
acidic
Describe the relationship between cystine crystals’ solubility and the pH of urine
in vivo, solubility of cystine rises exponentially with urine pH such that it is almost four times more soluble at pH 8 than at pH 5
How to differentiate disintegration forms of cystine in the presence of ammonia from colorless uric acid crystals ?
Uric acid crystals are very birefringent under polarized microscopy
- only thick cystine crystals have polarizing capability
- can be detected chemically with sodium cyanide
- sodium nitroprusside test
- dissolve in alkali and HCl (pH <2)
___ crystals in acidic urine appear as fine, delicate needles that are colourless or yellow. The needle clusters often appear to be black, especially in the center but they may take on a yellow colour in the presence of bilirubin.
Tyrosine
Tyrosine crystals are soluble in ___ and ____ but insoluble in ___
ammonium hydroxide
HCl
acetic acid
Why are tyrosine crystals rarely seen ?
they require refrigeration to force them out of solution
Although rare, tyrosine crystals have been observed in the urine of patients with ___
severe liver disease
These crystals are highly refractile, yellow, to brown spheres and can resemble fat globules when observed in acidic urine . They have concentric circles or radial striations on their surface
leucine crystals
Tyrosine crystals are often present in the urine of patients with ___, ___, and ____
cystinuria
tyrosinosis
oasthouse urine disease
Out of tyrosine and leucine crystals which is found more often in urine ?
tyrosine, because leucine is more soluble
Leucine is often present in urine of patients with ____ and although rare, ___
cystinuria
severe liver disease
These crystals are clear, fat, rectangular plates with notched corners present in acidic urine and can be in neutral urine. Because of the their organic composition, they are soluble in chloroform and ether.
Cholesterol
What is the rupture of lymphatic vessels into the renal tubules as a result of tumors, filariasis, and chronic renal disease referred to as ?
chyluria
Cholesterol crystals can be seen with ___ and in conditions resulting ____
nephrotic syndrome
chyluria
How to differentiate intravenous radiopaque contrast media forming flat and layered rectangular crystals that are similar to cholesterol crystals ?
radiopaque contrast media:
- high specific gravity
- not associated with lipiduria or proteinuria
cholesterol:
- low specific gravity
- associated with lipiduria or proteinuria
___ crystals are crystals induced in patients as a result of a particular treatment (e.g., medications)
Iatrogenic
Two common drugs are known for their ability to form crystals in urine
sulfonamides and ampicillin
These crystals are yellow-brown or colourless elongated prisms or plates occurring in clusters. In some instances, they may be thin enough to resemble needles. They are more soluble in water and ether than are uric acid crystals.
Hippuric acid
These crystals are long, colourless, thin prisms or needle-like crystals that may aggregate into small groupings or, with refrigeration into large clusters
Ampicillin
These are slender, feather-like crystals that aggregate into wing-like bundles, which can also associate into a rosette-like or cross form
Indinavir
What pH are indinavir more often observed ?
neutral and alkaline
These are highly refractile and birefringent crystals that appear as colourless to brown rosettes, spheres, whetstones or rhombic with irregular radial striations
sulfamethoxazole/sulfonamides
sulfamethoxazole/sulfonamides sometimes appear as bundles of needles that resemble sheaves of ___
wheat
sulfamethoxazole/sulfonamides constriction of the bundle may be located centrally or extremely eccentric, resulting in a ___
fan formation
What is the primary cause of sulfamethoxazole/sulfonamides ?
inadequate patient hydration
The appearance of sulfamethoxazole/sulfonamides in fresh urine can suggest the possibility of ___ or ____
UTI
tubular damage if crystals are forming in the nephron
These crystals appear as colourless, long, rectangular needles that occur singly or clustered in sheaves. When administered intravenously, they appear as flat elongated rectangular plates.
radiographic contrast media crystals
How to differentiate radiographic contrast media crystals and cholesterol crystals ?
radiographic contrast media crystals occur in large number in one field of view.
This is a fibrillar protein (some contain uromodulin) that comes from the renal tubules and vaginal epithelium.
Mucus threads
Mucus threads have a very low refractive index so what microscope should be used ?
phase contrast or interference contrast microscopy better visualize these
These miscellaneous elements are readily identified by their delicate, wavy, ribbon-like strands and irregular or serrated ends
Mucus threads
Some of the wider mucus threads may be confused with ____ or ____
cylindroids
hyaline casts
How to differentiate mucus threads from casts ?
cylindrical composition of casts and their rounded ends
What cases may mucus threads appear in increased numbers ?
inflammation or irritation of the urinary tract
These miscellaneous elements are highly refractile and appear colourless to yellow-green or even brownish
fats
Lipids are excreted in urine (lipiduria) in cases of ____, ____, _____, and _____
diabetes mellitus
damage to glomerulation filtration barrier like in nephrotic syndrome
extreme physical exercise
crush injuries
In ___, fat is often present and can persist for several weeks after delivery
preeclampsia
Oils and fats from these can contaminate urine
lubricants
ointments
creams
lotions
Urine from men with ____ may contain free-floating fat globules
prostatitis
Regardless of the source, these contaminating lipids are often indicated by ___, ____, and ____
lack of proteinuria
fatty casts
oval fat bodies
These miscellaneous elements appear as coarse yellow-brown granules and are difficult to distinguish from amorphous crystalline material in the sediment
hemosiderin
Hemosiderin is usually found 2-3 days after a severe hemolytic episode such as ___ and ___
transfusion reactions
paroxysmal nocturnal hemoglobinuria
Hemosiderin granules may be found free floating or within ___. ___. or ___
macrophages
casts
tubular epithelial cells
This is used to identify hemosiderin in the urine sediment and in tissues
prussian blue reaction aka rous test
Why is it important to report the presence of sperm in urine from females ?
it could potentially identify sexual abuse in underage and other vulnerable females
In urine from men, sperm can be present owing to ___, from ___
nocturnal emissions
normal or retrograde ejaculation
What is the most commonly encountered bacteria in urine
bacilli
The presence of bacteria in urine often reflects the contamination from these sources (4)
skin
vagina
gastrointestinal tract
may imply UTI or fistula between the urinary tract and the bowel
When bacteriuria is present without ____, the specimen collection and handling should be investigates
leukocytes
The presence of bacteria has clinical significance only if the urine specimen has been ___ and ____
properly collected
stored
These are ovoid, colourless cells, that are more refractile than erythrocytes and do not dissolve in acid and do not stain with supravital stains
characteristic budding form and pseudohyphae
yeast cells
certain situations such as ____ (6) may promote vaginal yeast infection
pregnancy
use of oral contraceptives
vaginal moniliasis
kidney disease
immunocompromised patients
diabetes mellitus
The most commonly encountered yeast in urine sediment is ____ and rarely found is ____, the latter is not involved in____ formation
candida albicans
candida glabrata
pseudohyphae
During microscopic examination a true yeast infection should be accompanied by the presence of ____
WBCs
Several parasites can be observed in the urine sediment. These include ___, ___, and ___ the former two being associated with ____ contamination
eggs of Enterobius vermicularis
cysts of Giarda lamblia
eggs of the blood fluke Schistosoma haematobium
fecal
This is the most common cause of parasitic gynecologic infection in female patients
Trichomonas vaginalis
This parasite appear as turnip-shaped flagellates with unicellular bodies averaging 15um in length
Trichomonas vaginalis
What is the method of collection for urine analysis of parasites ?
freshly collected as old specimen may no longer demonstrate their motility
Starch granule contamination may occur when ____
cornstarch is the power used in gloves
This contaminant have granules that are highly refractile spheres, usually with a dimpled center
Starch granules
This contaminant resemble fat droplets when polarized, producing a maltese cross formation
starch granules
Starch granules may also occasionally be confused with ___
RBCs
This contaminant is short to long, flat structures often mistaken for casts
fibers
How are fibers differentiated from casts ?
fibers: dark edges and flat
casts: no dark edges and cylindrical
