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AUBF Lecture > Lesson 4.2: Urinary Sediments (Crystals) > Flashcards

Lesson 4.2: Urinary Sediments (Crystals) Flashcards

1
Q

Crystals are formed by the precipitation of?

A

Urine solutes

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2
Q

Precipitation is subject to changes in _____, _____, and _____, which affect solubility

A

temperature, solute concentration, pH

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3
Q

True or False

Solutes precipitate more readily at low temperatures

A

True

The majority of crystal formation takes place in specimens that have remained at room temperature or have been refrigerated before testing

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4
Q

The presence of crystals in freshly voided urine is associated most frequently with low or high specific gravity specimens?

A

High specific gravity (concentrated)

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5
Q

What microscopic technique is used for crystal identification?

A

Polarized microscopy

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5
Q

It is a crystal that precipitates in both acidic and neutral urine

A

Calcium oxalate

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5
Q

True or False

The geometric shape of a crystal determines its birefringence and, therefore, its ability to polarize light

A

True

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5
Q

All abnormal crystals are found in what pH of the urine?

A

Acidic pH

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6
Q

What is the relationship of the speed of crystallization to the size of the crystals?

A

Inversely proportional

Slower crystallization = Larger crystals

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6
Q

Technical Tip: The most valuable initial aid for identifying crystals in a urine specimen is the pH

A

Copy po lods

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7
Q

Microscopically, most urate crystals appear _____ to _____ and are the only normal crystals found in acidic urine that appear colored

A

yellow to reddish brown

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7
Q

What are the most common crystals seen in Acidic Urine?

A

Urates
- amorphous urates
- uric acid
- acid urates
- sodium urates

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7
Q

Identify the Crystal

pH: Acid
Color: yellow-brown
Shape: rosettes, wedges

A

Uric acid

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7
Q

Identify the Crystal

pH: Alkaline/Neutral
Color: White-colorless

A

Amorphous phosphates

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7
Q

Identify the Crystal

pH: Acid
Color: Brick dust or yellow brown

A

Amorphous urates

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7
Q

Identify the Crystal

pH: Acid/neutral(alkaline)
Color: Colorless
Shape: Envelopes, oval, dumbbell

A

Calcium oxalate

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7
Q

Identify the Crystal

pH: Acid
Color: Colorless

A

Sodium urates

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8
Q

Identify the Crystal

pH: Alkaline/neutral
Color: Colorless

A

Calcium phosphate

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8
Q

Identify the Crystal

pH: Alkaline
Color: Colorless
Shape: “Coffin lids”

A

Triple phosphate

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9
Q

Identify the Crystal

pH: Alkaline
Color: Yellow-brown
Shape: “Thorny apples”

A

Ammonium biurate

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10
Q

Identify the Crystals

pH: Alkaline
Color: Colorless
Shape: “Dumbbells”

A

Calcium carbonate

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11
Q

These are frequently encountered in specimens that have been refrigerated but disappear when the urine is warmed

A

Amorphous urates

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12
Q

Amorphous urates produce a very characteristic pink sediment caused by the accumulation of the pigment __________ on the surface of the granules

A

uroerythrin

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12
Q

These are crystals seen in patients with:

Leukemia who are receiving chemotherapy Lesch-Nyhan Syndrome
Gout patients

A

Uric acid

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13
Q

Uric acid crystals have a variety of shapes like?

A

rhombic
four-sided flat plates (whetstones)
wedges
rosettes

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14
Q

These appear as larger granules and may have “spicules” similar to ammonium biurate crystals seen in alkaline urine

A

Acid urates

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14
Q

What makes six-sided uric acid crystals different from cystine crystals?

A

Uric acid crystals are birefringent under polarized light

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14
Q

Six-sided uric acid crystals can be similar to what crystals?

A

Cystine crystals

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14
Q

These are “needle-shaped” crystals and are seen in “synovial fluid” during episodes of gout

A

Sodium urate

14
Q

Increased amounts of uric acid crystals, particularly in fresh urine, are associated with increased levels of ______ and ______

A

purines and nucleic acids

15
Q

Most common form of calcium oxalate that is easily recognized as colorless, octahedral envelope or as two pyramids joined at their bases

A

Dihydrate

15
Q

This is a form of calcium oxalate that is oval or dumbbell shaped

A

Monohydrate form

16
Q

It is an end product of ascorbic acid metabolism

A

Oxalic acid

16
Q

These crystals are associated with foods high in oxalic acid, such as tomatoes and asparagus, and ascorbic acid because oxalic acid is an end product of ascorbic acid metabolism

A

Calcium oxalate

16
Q

Majority of renal calculi are composed of?

A

Calcium oxalate

17
Q

The primary pathological significance of calcium oxalate crystals is the very noticeable presence of the monohydrate form (dumbbell) in cases of?

A

ethylene glycol (antifreeze) poisoning

18
Q

This form of calcium oxalate is commonly seen in pets and children because antifreeze tastes sweet and uncovered containers left in the garage can be very tempting

A

Monohydrate form

19
Q

Phosphates represent the majority of crystals in alkaline urine and include?

A

Amorphous phosphate
Triple phosphate
Calcium phosphate

20
Q

When present in large quantities after specimen refrigeration, they cause a white precipitate that does not dissolve on warming

A

Amorphous phosphates

21
Q

Identified easily by their “prism” shape that frequently resembles a “coffin lid” appearance

A

Triple Phosphate

21
Q

Other name of triple phosphate

A

ammonium magnesium phosphate

21
Q

Aside from calcium oxalate, what is a common constituent of renal calculi?

A

Calcium phosphate

22
Q

These crystals are often seen in highly alkaline urine associated with the presence of “urea-splitting” bacteria

A

Triple phosphate

22
Q

They appear as colorless, rectangular plates or thin prisms often in rosette formations.

A

Calcium phosphate

22
Q

How to differentiate calcium phosphate crystals and sulfonamides?

A

Acetic acid

Calcium phosphates dissolve in dilute acetic acid, but sulfonamides do not

23
Q

The rosette form of calcium phosphates may be confused with __________ when the urine pH is in the neutral range

A

Sulfonamide crystals

23
Q

Ammonium biurate crystals and with other urates dissolve at 60C and convert to uric acid crystals when ________ is added

A

glacial acetic acid

23
Q

These are crystals that resemble amorphous material, but they can be distinguished by the formation of gas after the addition of acetic acid

A

Calcium carbonate

24
Q

Exhibit the characteristic yellow-brown color of the urate crystals seen in acidic urine.

Described as “thorny apples” because of their appearance as “spicule-covered” spheres

A

Ammonium biurate

25
Q

These 2 crystals are associated with the presence of urea-splitting bacteria

A

Triple Phosphate
Ammonium Biurate

26
Q

These are found in people who inherit a metabolic disorder that prevents reabsorption of cystine by the renal tubules (cystinuria)

A

Cystine crystals

27
Q

At an old age, people with cystinuria tend to form what?

A

Renal calculi

28
Q

What test is is used for the positive confirmation of cystine crystals?

A

Cyanide-nitroprusside test

28
Q

Colorless , Hexagonal plates, and may be thick or thin

A

Cystine crystals

29
Q

Identify the Abnormal Crystal

pH: Acid
Color: Colorless
Form: Hexagonal Plate
Disorder: Inherited cystinuria

A

Cystine crystals

30
Q

They resemble a “rectangular plate” with a notch in one or more corners

A

Cholesterol crystals

31
Q

Identify the Abnormal Crystal

pH: Acid
Color: Colorless
Form: Notched plates
Disorders: Nephrotic Syndrome

A

Cholesterol

32
Q

Identify the Abnormal Crystal

pH: Acid/Neutral
Color: Yellow
Form: Concentric circles
Disorder: Liver Disease

A

Leucine

33
Q

Identify the Abnormal Crystal

pH: Acid/neutral
Color: colorless-yellow
Form: Needles
Disorder: Liver Disease

A

Tyrosine

34
Q

Identify the Abnormal Crystal

pH: Acid
Color: Yellow
Disorder: Liver Disease

A

Bilirubin

34
Q

Identify the Abnormal Crystal

pH: Acid/neutral
Color: Colorless
Form: Needles
Disorder: Infection treatment

A

Ampicillin

35
Q

Identify the Abnormal Crystal

pH: Acid/neutral
Color: Varied
Disorder: Infection treatment

A

Sulfonamides

35
Q

Identify the Abnormal Crystal

pH: Acid
Color: Colorless
Form: Flat plates
Disorder: Radiographic procedure

A

Radiographic dye

36
Q

3 crystals usually seen in cases of Liver Disorders

A

Leucine
Tyrosine
Bilirubin

37
Q

This abnormal crystal is usually encountered with inherited disorders of amino acid metabolism

A

Tyrosine crystals

38
Q

What is the primary cause of sulfonamide crystallization?

A

Dehydration

39
Q

These appear as colorless needles that tend to form bundles after refrigeration and encountered after massive doses of penicillin without adequate hydration

A

Ampicillin

40
Q

These are “seasonal contaminants” that appear as spheres with a cell wall and occasional concentric circles

A

Pollen grains

40
Q

Artifacts with a “dimpled center”

A

Starch

41
Q

Technical Tip: Use polarized microscopy to differentiate between fibers, which polarize, and casts, which do not (except for fatty casts)

A

YESSIR!

AUBF Lecture (7 decks)

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