Lesson 4.2: Urinary Sediments (Crystals) Flashcards
Crystals are formed by the precipitation of?
Urine solutes
Precipitation is subject to changes in _____, _____, and _____, which affect solubility
temperature, solute concentration, pH
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
The presence of crystals in freshly voided urine is associated most frequently with low or high specific gravity specimens?
High specific gravity (concentrated)
What microscopic technique is used for crystal identification?
Polarized microscopy
It is a crystal that precipitates in both acidic and neutral urine
Calcium oxalate
True or False
The geometric shape of a crystal determines its birefringence and, therefore, its ability to polarize light
True
All abnormal crystals are found in what pH of the urine?
Acidic pH
What is the relationship of the speed of crystallization to the size of the crystals?
Inversely proportional
Slower crystallization = Larger crystals
Technical Tip: The most valuable initial aid for identifying crystals in a urine specimen is the pH
Copy po lods
Microscopically, most urate crystals appear _____ to _____ and are the only normal crystals found in acidic urine that appear colored
yellow to reddish brown
What are the most common crystals seen in Acidic Urine?
Urates
- amorphous urates
- uric acid
- acid urates
- sodium urates
Identify the Crystal
pH: Acid
Color: yellow-brown
Shape: rosettes, wedges
Uric acid
Identify the Crystal
pH: Alkaline/Neutral
Color: White-colorless
Amorphous phosphates
Identify the Crystal
pH: Acid
Color: Brick dust or yellow brown
Amorphous urates
Identify the Crystal
pH: Acid/neutral(alkaline)
Color: Colorless
Shape: Envelopes, oval, dumbbell
Calcium oxalate
Identify the Crystal
pH: Acid
Color: Colorless
Sodium urates
Identify the Crystal
pH: Alkaline/neutral
Color: Colorless
Calcium phosphate
Identify the Crystal
pH: Alkaline
Color: Colorless
Shape: “Coffin lids”
Triple phosphate
Identify the Crystal
pH: Alkaline
Color: Yellow-brown
Shape: “Thorny apples”
Ammonium biurate
Identify the Crystals
pH: Alkaline
Color: Colorless
Shape: “Dumbbells”
Calcium carbonate
These are frequently encountered in specimens that have been refrigerated but disappear when the urine is warmed
Amorphous urates
Amorphous urates produce a very characteristic pink sediment caused by the accumulation of the pigment __________ on the surface of the granules
uroerythrin
These are crystals seen in patients with:
Leukemia who are receiving chemotherapy Lesch-Nyhan Syndrome
Gout patients
Uric acid
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!
