Lesson 4.2: Urinary Sediments (Crystals) Flashcards by Merch Paul Eli Silvederio

Crystals are formed by the precipitation of?

Urine solutes

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

temperature, solute concentration, pH

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True or False

Solutes precipitate more readily at low temperatures

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

High specific gravity (concentrated)

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What microscopic technique is used for crystal identification?

Polarized microscopy

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

Calcium oxalate

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True or False

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

True

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

Acidic pH

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

Inversely proportional

Slower crystallization = Larger crystals

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

Copy po lods

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

yellow to reddish brown

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What are the most common crystals seen in Acidic Urine?

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

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Identify the Crystal

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

Uric acid

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Identify the Crystal

pH: Alkaline/Neutral
Color: White-colorless

Amorphous phosphates

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Identify the Crystal

pH: Acid
Color: Brick dust or yellow brown

Amorphous urates

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Identify the Crystal

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

Calcium oxalate

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Identify the Crystal

pH: Acid
Color: Colorless

Sodium urates

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Identify the Crystal

pH: Alkaline/neutral
Color: Colorless

Calcium phosphate

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Identify the Crystal

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

Triple phosphate

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Identify the Crystal

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

Ammonium biurate

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Identify the Crystals

pH: Alkaline
Color: Colorless
Shape: “Dumbbells”

Calcium carbonate

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

Amorphous urates

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

uroerythrin

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These are crystals seen in patients with:

Leukemia who are receiving chemotherapy Lesch-Nyhan Syndrome
Gout patients

Uric acid

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Uric acid crystals have a variety of shapes like?

rhombic four-sided flat plates (whetstones) wedges rosettes

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

Acid urates

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

Uric acid crystals are birefringent under polarized light

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

Cystine crystals

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

Sodium urate

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

purines and nucleic acids

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

Dihydrate

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

Monohydrate form

It is an end product of ascorbic acid metabolism

Oxalic acid

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

Calcium oxalate

Majority of renal calculi are composed of?

Calcium oxalate

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

ethylene glycol (antifreeze) poisoning

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

Monohydrate form

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

Amorphous phosphate Triple phosphate Calcium phosphate

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

Amorphous phosphates

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

Triple Phosphate

Other name of triple phosphate

ammonium magnesium phosphate

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

Calcium phosphate

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

Triple phosphate

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

Calcium phosphate

How to differentiate calcium phosphate crystals and sulfonamides?

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

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

Sulfonamide crystals

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

glacial acetic acid

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

Calcium carbonate

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

Ammonium biurate

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

Triple Phosphate Ammonium Biurate

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

Cystine crystals

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

Renal calculi

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

Cyanide-nitroprusside test

Colorless , Hexagonal plates, and may be thick or thin

Cystine crystals

Identify the Abnormal Crystal pH: Acid Color: Colorless Form: Hexagonal Plate Disorder: Inherited cystinuria

Cystine crystals

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

Cholesterol crystals

Identify the Abnormal Crystal pH: Acid Color: Colorless Form: Notched plates Disorders: Nephrotic Syndrome

Cholesterol

Identify the Abnormal Crystal pH: Acid/Neutral Color: Yellow Form: Concentric circles Disorder: Liver Disease

Leucine

Identify the Abnormal Crystal pH: Acid/neutral Color: colorless-yellow Form: Needles Disorder: Liver Disease

Tyrosine

Identify the Abnormal Crystal pH: Acid Color: Yellow Disorder: Liver Disease

Bilirubin

Identify the Abnormal Crystal pH: Acid/neutral Color: Colorless Form: Needles Disorder: Infection treatment

Ampicillin

Identify the Abnormal Crystal pH: Acid/neutral Color: Varied Disorder: Infection treatment

Sulfonamides

Identify the Abnormal Crystal pH: Acid Color: Colorless Form: Flat plates Disorder: Radiographic procedure

Radiographic dye

3 crystals usually seen in cases of Liver Disorders

Leucine Tyrosine Bilirubin

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

Tyrosine crystals

What is the primary cause of sulfonamide crystallization?

Dehydration

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

Ampicillin

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

Pollen grains

Artifacts with a "dimpled center"

Starch

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

YESSIR!