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AUBF LAB > M4U3: URINARY CRYSTALS AND MISCELLANEOUS ELEMENTS > Flashcards

M4U3: URINARY CRYSTALS AND MISCELLANEOUS ELEMENTS Flashcards

1
Q

Crystals which are frequently found in acidic urine

A

uric acid
calcium oxalate
amorphous urates

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2
Q

Crystals not frequently found in urine

A 
calcium sulfate
sodium urates
hippuric acids
cystine
leucine
tyrosine
cholesterol
sulfa
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3
Q

factors affecting formation of crystals

A

urine pH
concentration of solute in urine
flow of urine through the tubules
temperature

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4
Q

Why is microscopic evaluation of urine is important for detection of crystals ?

A

no or very limited chemical tests detect their presence

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5
Q

___ represent the majority of crystals seen in alkaline urine and include ___, ____, and ___

A

phosphates

amorphous phosphate
triple phosphate
calcium phosphate

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6
Q

Microscopically, these appear as small, yellow-brown granules much like sand

A

amorphous urates

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7
Q

Sometimes amorphous urates may appear in clumps and may resemble a formed element

A

granular casts

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8
Q

___ are frequently encountered in specimens that have been refrigerated and produce a very characteristic pink sediment

A

amorphous urates

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9
Q

The characteristic pink sediment produced by refrigerated amorphous urates is due to the accumulation of what pigment ?

A

uroerythrin

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10
Q

Amorphous urates are found in acidic urine in what pH ?

A

greater than 5.5

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11
Q

This urine crystal appears as small, yellow-brown balls or spheres

A

acid urates

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12
Q

acid urates are often misidentified as ___

A

leucine crystals

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13
Q

Acid urates appear as larger granules and may have spicules similar to the ____ crystals seen in alkaline urine

A

ammonium biurate

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14
Q

Acid urate crystals can be present when the urine pH is ___ but frequently are not observed in fresh urine

A

neutral to slightly acidic

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15
Q

What urine crystals dissolve at 60C ?

A

acid urates

monosodium urates

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16
Q

Acid urates can be converted to uric acid crystals by the addition of ____

A

glacial acetic acid

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17
Q

These are distinct form of a uric acid salt which appears as colourless to light-yellow slender, pencil-like prisms

A

monosodium urates

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18
Q

These urine crystals are seen in synovial fluid during episodes of gout, and can appear in urine

A

monosodium urates

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19
Q

____ and ___ are solutes normally found in the urine of healthy individuals

A

calcium

oxalate

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20
Q

Approximately 50% of the oxalate typically present in urine is derived from ___ or from ____

A 
ascorbic acid (vitamin C)
oxalic acid
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21
Q

These foods are high in oxalic acid

A

vegetables (rhubarb, tomatoes, asparagus, spinach)

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22
Q

These beverages are high in oxalic acid

A

cocoa
tea
coffee
chocolate

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23
Q

Which form of calcium oxalate less common ?

A

monohydrate form

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24
Q

This urine crystal is octahedral or pyramidal in shape

A

dihydrate calcium oxalate

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25
Q

When this urine crystal is viewed from one end, they appear as squares scribed with lined that intersect in the center

A

dihydrate calcium oxalate

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26
Q

This urine crystal is sometimes called enveloped crystals

A

dihydrate calcium oxalate

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27
Q

This urine crystal is small and ovoid or dumbbell shaped and can resemble RBCs

A

monohydrate calcium oxalate

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28
Q

____ crystals may cluster together and can stick to mucous threads. When this occurs, they may be mistaken for crystal casts.

A

calcium oxalate

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29
Q

What colour is calcium oxalate identified by ?

A

they are colourless

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30
Q

___ crystals are the most frequently observed crystals in human urine

A

calcium oxalate

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31
Q

why is calcium oxalate the most frequently observed crystals in human urine ?

A

can form in urine of any pH

greatly affected by diet

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32
Q

What may cause an increase in numbers of calcium oxalate crystals ?

A

ingestion of the oxalate precursor ethylene glycol (antifreeze)

during severe chronic renal disease

diabetes mellitus

liver disease

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33
Q

Uric acid crystals are seen in a variety of shapes and these include ? (7)

A

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

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34
Q

These urine crystals usually appear yellow to golden brown and the intensity of their colour varies directly with the thickness of the crystal

A

uric acid crystals

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35
Q

What may be the reason for uric acid appearing colourless ?

A

thin or when urine is low in uroerythrin

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36
Q

These crystals under polarizing microscopy exhibit a strong birefringence and produce a variety of interference colours

A

uric acid crystals

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37
Q

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

A

5.7

ionized

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38
Q

Generally, uric acid crystals are 17 times less soluble than _____ crystals

A

urate salt

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39
Q

Uric acid is a normal urine solute that originates from ___

A

catabolism of purine nucleosides (adenosine and guanosine from RNA and DNA)

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40
Q

increased amounts of urinary uric acid can be present in these instances

A

administration of cytotoxic drugs (e.g., chemotherapeutic agent)

gout

patients with Lesch-Nyahn Syndrome

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41
Q

These are non-crystalline form of phosphates that resemble fine, colourless grains of sands in the sediment

A

amorphous phosphates

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42
Q

These granular particles which are also found in neutral urine have no definite shape and are usually microscopically indistinguishable from amorphous urates

A

amorphous phosphates

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43
Q

How to differentiate amorphous phosphates and amorphous urates ?

A

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
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44
Q

Why is triple phosphate referred to as that ?

A

ammonium
magnesium
phosphate

materials

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45
Q

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”

A

Triple phosphate

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46
Q

With prolonged storage, these crystals can dissolve, taking on a feather form that resembles a fern leaf

A

triple phosphate

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47
Q

Triple phosphate crystals have been associated with ____ and have been implicated in ___

A

UTI

formation of renal calculi

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48
Q

This urine crystal is present in any urine pH as dibasic and monobasic

A

calcium phosphate

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49
Q

calcium phosphate as dibasic is

A

calcium monohydrogen phosphate

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50
Q

calcium phosphate as monobasic calcium phosphate is

A

calcium biphosate

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51
Q

dibasic calcium phosphate crystals sometimes called stellar phosphates, appear as ___ (6)

A

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

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52
Q

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 ?

A

dibasic forms dissolve in dilute acetic acid while sulfonamides do not

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53
Q

___ 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

A

monobasic calcium phosphate

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54
Q

Monobasic calcium phosphate can resemble ___

A

large degenerating squamous epithelial cells

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55
Q

Both types of calcium phosphate have no clinical significance, though calcium phosphate is a common constituent of ___

A

renal calculi

56
Q

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

A

Magnesium phosphate

57
Q

What is a characteristic of monobasic calcium phosphate crystals with polarizing microscopy ?

A

weakly birefringent

58
Q

What is a characteristic of magnesium phosphate crystals with polarizing microscopy ?

A

weakly birefringent

59
Q

These are yellow-brown spherical crystals with striations/projections or spicules on the surface giving them a “thorny apple” appearance

A

Ammonium biurate

60
Q

Ammonium biurate occur most frequently in urine specimens that have undergone ____

A

prolonged storage

61
Q

Why is ammonium biurate only clinically significantly when they form precipitate in fresh urine specimens

A

because in vivo precipitation can cause renal tubular damage

62
Q

What is a characteristic of ammonium biurate crystals with polarizing microscopy ?

A

strongly birefringent

63
Q

What are ways to dissolve ammonium biurate ?

A

acetic acid

heating to 60C

64
Q

Similar to other urate salts, ammonium biurate can be converted to uric acid crystals with the addition of ___

A

concentrated HCl or acetic acid

65
Q

Ammonium biurate can resemble some forms of ___

A

sulfonamide crystals

66
Q

These urine crystals are tiny, colourless granular crystals that assume dumbbell, spherical or tetrad shapes and is slightly larger than amorphous material

A

calcium carbonate

67
Q

How are calcium carbonate crystals differentiated from amorphous materials ?

A

formation of gas after the addition of acetic acid

68
Q

How are calcium carbonate crystals differentiated from bacteria ?

A

calcium carbonate are birefringent

69
Q

Abnormal urine crystals are mostly found at what pH ?

A

acidic

70
Q

These crystals usually appear yellow-brown small clusters of fine needles, and sometimes in granules and plates and only form in acidic urine

A

bilirubin

71
Q

Why are bilirubin classified as abnormal crystals ?

A

because bilirubinuria indicates a metabolic disease process

72
Q

These crystals are clear, colourless, hexagonal plates with uneven sides, They are often refractile, laminated or layered and tend to clump.

A

cystine crystals

73
Q

What pH can cystine crystals be primarily found at ?

A

acidic

74
Q

Describe the relationship between cystine crystals’ solubility and the pH of urine

A

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

75
Q

How to differentiate disintegration forms of cystine in the presence of ammonia from colorless uric acid crystals ?

A

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)
76
Q

___ 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.

A

Tyrosine

77
Q

Tyrosine crystals are soluble in ___ and ____ but insoluble in ___

A

ammonium hydroxide
HCl

acetic acid

78
Q

Why are tyrosine crystals rarely seen ?

A

they require refrigeration to force them out of solution

79
Q

Although rare, tyrosine crystals have been observed in the urine of patients with ___

A

severe liver disease

80
Q

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

A

leucine crystals

81
Q

Tyrosine crystals are often present in the urine of patients with ___, ___, and ____

A

cystinuria
tyrosinosis
oasthouse urine disease

82
Q

Out of tyrosine and leucine crystals which is found more often in urine ?

A

tyrosine, because leucine is more soluble

83
Q

Leucine is often present in urine of patients with ____ and although rare, ___

A

cystinuria

severe liver disease

84
Q

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.

A

Cholesterol

85
Q

What is the rupture of lymphatic vessels into the renal tubules as a result of tumors, filariasis, and chronic renal disease referred to as ?

A

chyluria

86
Q

Cholesterol crystals can be seen with ___ and in conditions resulting ____

A

nephrotic syndrome

chyluria

87
Q

How to differentiate intravenous radiopaque contrast media forming flat and layered rectangular crystals that are similar to cholesterol crystals ?

A

radiopaque contrast media:

  • high specific gravity
  • not associated with lipiduria or proteinuria

cholesterol:

  • low specific gravity
  • associated with lipiduria or proteinuria
88
Q

___ crystals are crystals induced in patients as a result of a particular treatment (e.g., medications)

A

Iatrogenic

89
Q

Two common drugs are known for their ability to form crystals in urine

A

sulfonamides and ampicillin

90
Q

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.

A

Hippuric acid

91
Q

These crystals are long, colourless, thin prisms or needle-like crystals that may aggregate into small groupings or, with refrigeration into large clusters

A

Ampicillin

92
Q

These are slender, feather-like crystals that aggregate into wing-like bundles, which can also associate into a rosette-like or cross form

A

Indinavir

93
Q

What pH are indinavir more often observed ?

A

neutral and alkaline

94
Q

These are highly refractile and birefringent crystals that appear as colourless to brown rosettes, spheres, whetstones or rhombic with irregular radial striations

A

sulfamethoxazole/sulfonamides

95
Q

sulfamethoxazole/sulfonamides sometimes appear as bundles of needles that resemble sheaves of ___

A

wheat

96
Q

sulfamethoxazole/sulfonamides constriction of the bundle may be located centrally or extremely eccentric, resulting in a ___

A

fan formation

97
Q

What is the primary cause of sulfamethoxazole/sulfonamides ?

A

inadequate patient hydration

98
Q

The appearance of sulfamethoxazole/sulfonamides in fresh urine can suggest the possibility of ___ or ____

A

UTI

tubular damage if crystals are forming in the nephron

99
Q

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.

A

radiographic contrast media crystals

100
Q

How to differentiate radiographic contrast media crystals and cholesterol crystals ?

A

radiographic contrast media crystals occur in large number in one field of view.

101
Q

This is a fibrillar protein (some contain uromodulin) that comes from the renal tubules and vaginal epithelium.

A

Mucus threads

102
Q

Mucus threads have a very low refractive index so what microscope should be used ?

A

phase contrast or interference contrast microscopy better visualize these

103
Q

These miscellaneous elements are readily identified by their delicate, wavy, ribbon-like strands and irregular or serrated ends

A

Mucus threads

104
Q

Some of the wider mucus threads may be confused with ____ or ____

A

cylindroids

hyaline casts

105
Q

How to differentiate mucus threads from casts ?

A

cylindrical composition of casts and their rounded ends

106
Q

What cases may mucus threads appear in increased numbers ?

A

inflammation or irritation of the urinary tract

107
Q

These miscellaneous elements are highly refractile and appear colourless to yellow-green or even brownish

A

fats

108
Q

Lipids are excreted in urine (lipiduria) in cases of ____, ____, _____, and _____

A

diabetes mellitus

damage to glomerulation filtration barrier like in nephrotic syndrome

extreme physical exercise

crush injuries

109
Q

In ___, fat is often present and can persist for several weeks after delivery

A

preeclampsia

110
Q

Oils and fats from these can contaminate urine

A

lubricants
ointments
creams
lotions

111
Q

Urine from men with ____ may contain free-floating fat globules

A

prostatitis

112
Q

Regardless of the source, these contaminating lipids are often indicated by ___, ____, and ____

A

lack of proteinuria
fatty casts
oval fat bodies

113
Q

These miscellaneous elements appear as coarse yellow-brown granules and are difficult to distinguish from amorphous crystalline material in the sediment

A

hemosiderin

114
Q

Hemosiderin is usually found 2-3 days after a severe hemolytic episode such as ___ and ___

A

transfusion reactions

paroxysmal nocturnal hemoglobinuria

115
Q

Hemosiderin granules may be found free floating or within ___. ___. or ___

A

macrophages

casts

tubular epithelial cells

116
Q

This is used to identify hemosiderin in the urine sediment and in tissues

A

prussian blue reaction aka rous test

117
Q

Why is it important to report the presence of sperm in urine from females ?

A

it could potentially identify sexual abuse in underage and other vulnerable females

118
Q

In urine from men, sperm can be present owing to ___, from ___

A

nocturnal emissions

normal or retrograde ejaculation

119
Q

What is the most commonly encountered bacteria in urine

A

bacilli

120
Q

The presence of bacteria in urine often reflects the contamination from these sources (4)

A

skin

vagina

gastrointestinal tract

may imply UTI or fistula between the urinary tract and the bowel

121
Q

When bacteriuria is present without ____, the specimen collection and handling should be investigates

A

leukocytes

122
Q

The presence of bacteria has clinical significance only if the urine specimen has been ___ and ____

A

properly collected

stored

123
Q

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

A

yeast cells

124
Q

certain situations such as ____ (6) may promote vaginal yeast infection

A

pregnancy

use of oral contraceptives

vaginal moniliasis

kidney disease

immunocompromised patients

diabetes mellitus

125
Q

The most commonly encountered yeast in urine sediment is ____ and rarely found is ____, the latter is not involved in____ formation

A

candida albicans

candida glabrata

pseudohyphae

126
Q

During microscopic examination a true yeast infection should be accompanied by the presence of ____

A

WBCs

127
Q

Several parasites can be observed in the urine sediment. These include ___, ___, and ___ the former two being associated with ____ contamination

A

eggs of Enterobius vermicularis

cysts of Giarda lamblia

eggs of the blood fluke Schistosoma haematobium

fecal

128
Q

This is the most common cause of parasitic gynecologic infection in female patients

A

Trichomonas vaginalis

129
Q

This parasite appear as turnip-shaped flagellates with unicellular bodies averaging 15um in length

A

Trichomonas vaginalis

130
Q

What is the method of collection for urine analysis of parasites ?

A

freshly collected as old specimen may no longer demonstrate their motility

131
Q

Starch granule contamination may occur when ____

A

cornstarch is the power used in gloves

132
Q

This contaminant have granules that are highly refractile spheres, usually with a dimpled center

A

Starch granules

133
Q

This contaminant resemble fat droplets when polarized, producing a maltese cross formation

A

starch granules

134
Q

Starch granules may also occasionally be confused with ___

A

RBCs

135
Q

This contaminant is short to long, flat structures often mistaken for casts

A

fibers

136
Q

How are fibers differentiated from casts ?

A

fibers: dark edges and flat
casts: no dark edges and cylindrical

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