Crystalline Inclusions

Question 1

Amorphous Phosphates and Urates Macroscopic Appearance

Answer 1

Amorphous Phosphates produce a white precipitate in urine with an alkaline pH

Amorphous Urates produce a precipitate in acidic urine that resembles pink brick dust due to the presence of uroerythrin.

Question 2

Temperature Effect on Crystal Precipitation

Answer 2

Solutes precipitate more readily at low temperatures. Therefore, the majority of crystal formation takes place in specimens that have remained at room temperature or been refrigerated prior to testing.

Question 3

pH Effect on Precipitation

Answer 3

Organic and iatrogenic compounds crystallize more easily in an acidic pH

Inorganic salts are less soluble in neutral and alkaline solutions.

Question 4

Most Common Crystals Seen in Acidic Urine

Answer 4

Urates, consisting of amorphous urates, uric acid, acid urates, and sodium urates.

Question 5

Acidic Urine Crystals

Answer 5

• Amorphous Urates
• Calcium Oxalate
• Uric Acid
• Acid Urates
• Sodium Urate

Question 6

Amorphous Urates

Answer 6

Frequently encountered in specimens that have been refrigerated and produce a very characteristic pink sediment.

Question 7

Calcium Oxalate Crystals, Clinical Significance

Answer 7

Precipitates in both acidic and neutral urine, Monohydrate calcium oxalate crystals are oval or dumbbell shaped. Both forms are birefringent.

Because oxalic acid is an end product of ascorbic acid metabolism, the primary pathologic significance of calcium oxalate crystals is the presence of the monohydrate form in ethylene glycol poisoning.

Question 8

Uric Acid Crystals

Answer 8

Seen in a variety of shapes, are highly birefringent under polarized light

Increased amounts of uric acid crystals are associated with increased levels of purines and nucleic acids seen in patients receiving chemotherapy

Question 9

Acid Urates

Answer 9

Appear as larger granules and may have spicules similar to the ammonium biurate crystals seen in alkaline urine.

Question 10

Sodium Urate

Answer 10

Needle-shaped and are seen in synovial fluid during episodes of gout, but may also appear in the urine.

Question 11

Alkaline Urine Crystals

Answer 11

• Triple Phosphates
• Calcium Phosphate
• Calcium Carbonate
• Cystine
• Cholesterol
• Radiographic Dye Media

Question 12

Phosphates

Answer 12

Majority of the crystals seen in alkaline urine and include amorphous phosphate, triple phosphate, and calcium phosphate. If present in large quantities following specimen refrigeration, they form white precipitate that does not dissolve on warming. Differentiated from amorphous urates by the color of the sediment and urine pH.

Question 13

Triple Phosphate Crystals

Answer 13

Birefringent under polarized light, often seen in highly alkaline urine, associated with urea-splitting bacteria.

Question 14

Calcium Phosphate Crystals

Answer 14

Not frequently encountered. They may appear as colorless, flat rectangular plates or thin prisms often in rosette formations. Common constituent of renal calculi

Question 15

Calcium Carbonate Crystals

Answer 15

Small and colorless, with dumbbell or spherical shapes, may occur in clumps that resemble amorphous material, distinguished by the formation of gas after the addition of acetic acid (they convert to Uric Acid crystals). They are also birefringent.

Question 16

Cystine

Answer 16

Positive confirmation is made using the cyanide-nitroprusside test

Question 17

Cholesterol Crystals

Answer 17

Rarely seen unless specimens have been refrigerated, because the lipids remain in droplet form, highly birefringent

Question 18

Radiographic Contrast Media

Answer 18

Have a very similar appearance to cholesterol crystals and also are highly birefringent. Differentiation is best made by comparison of the other urinalysis results and patient history.

Question 19

Crystals in Severe Liver Disorders

Answer 19

Tyrosine, Leucine, and Bilirubin

Question 20

Tyrosine

Answer 20

Crystals appear as fine colorless to yellow needles that frequently form clumps or rosettes

Question 21

Leucine

Answer 21

Crystals are yellow-brown spheres that demonstrate concentric circles and radial striations

Question 22

Bilirubin

Answer 22

Crystals are present in hepatic disorders producing large amounts of bilirubin in the urine. They appear as clumped needles or granules with the characteristic yellow color of bilirubin

Question 23

Sulfonamide

Answer 23

Inadequate patient hydration is the primary cause of sulfonamide crystallization. The appearance of sulfonamide crystals in fresh urine can suggest the possibility of tubular damage if crystals are forming in the nephron. Shapes most frequently encountered include needles, rhombics, whetstones, sheaves of wheat, and rosettes with colors ranging from colorless to yellow-brown

Question 24

Ampicillin

Answer 24

Crystals following massive doses of this penicillin compound without adequate hydration. Ampicillin crystals appear as colorless needles that tend to form bundles following refrigeration

Question 25

Starch

Answer 25

The granules are highly refractile spheres, usually with a dimpled center resembling fat droplets; when polarized, producing a Maltese cross formation.

Question 26

Acidic Urine

Answer 26

Amorphous Urates

Question 27

Acidic Urine

Answer 27

Calcium Oxalate

Question 28

Acidic Urine

Answer 28

Uric Acid Crystals

Question 29

Acidic Urine

Answer 29

Monohydrate Calcium Oxalate

Question 30

Alkaline Urine

Answer 30

Amorphous Phosphate

Question 31

Alkaline Urine

Answer 31

Triple Phosphate

Question 32

Alkaline Urine

Answer 32

Calcium Carbonate

Question 33

Alkaline Urine

Answer 33

Cystine

Question 34

Alkaline Urine

Answer 34

Cholesterol

Question 35

Answer 35

Tyrosine

Question 36

Answer 36

Leucine

Question 37

Answer 37

Bilirubin

Question 38

Answer 38

Sulfonamide

Question 39

Answer 39

Ampicillin