3. Crystals

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3.1 Crystals
3.1.A Amorphous
3.1.B Calcium Oxalate
3.1.C Hippuric Acid
3.1.D Sodium Urate
3.1.E Uric Acid
3.1.F Ammonium Biurate
3.1.G Calcium Carbonate
3.1.H Calcium Phosphate
3.1.I Triple Phosphate
3.1.J Bilirubin
3.1.K Cystine
3.1.L Cholesterol
3.1.M Leucine
3.1.N Tyrosine
3.1.O Sulfonamide
3.1.P Radiographic Dye
3.1.Q Ampicillin

3.1 Crystals

Crystals are the product of precipitation of solutes in urine. There are multiple variables that contribute to crystallization of solutes in urine including decreased temperature, solute concentration, and pH. The purpose of identification is to detect abnormal urinary crystals that are clinically significant and are associated with disease.

Crystal	pH	Morphology & Color	Normal or Abnormal Disease Association
Amorphous Urates	Acidic	•Non-crystalline, no defined size or shape •Colorless, Yellow, Pink, Brown	Normal
Calcium Oxalate	Acidic to slightly Alkaline	•Octahedral (envelope), ovoid, rectangular, dumbbell •Colorless •Birefringent	Normal
Hippuric Acid	Acidic	•Six sided prisms, needles, rhombic plates •Colorless	Normal
Sodium Urate	Acidic	•Thin rectangular sticks •Colorless or Yellow	Normal
Uric Acid	Acidic	•Barrel, rhombic, rosettes, 6-sided •Colorless, Yellow, Brown •Birefringent	Normal
Amorphous Phosphates	Alkaline	•Non-crystalline, no defined size or shape •Colorless, Yellow, White	Normal
Ammonium Biurate	Alkaline	•Round, “Thorny Apple”, •Yellow, Brown	Normal
Calcium Carbonate	Alkaline	•Dumbbell, round •Colorless	Normal
Calcium Phosphate	Alkaline	•Wedge, flat plates, rosettes •Colorless	Normal
Triple Phosphate	Alkaline	•Prism shaped, “Coffin lid”, triangle •Colorless •Birefringent	Normal
Bilirubin	Acidic	•Needles or round with needle projections (needles often stick to WBC) •Yellow, Orange	Abnormal Liver disease
Cystine	Acidic	•Hexagonal plates •Colorless	Abnormal Cystinuria
Cholesterol	Acidic	•Flat plates with notched corners •Colorless •Birefringent	Abnormal Nephrotic syndrome
Leucine	Acidic	•Round with concentric rings, radial striations on outer edge •Yellow, Brown	Abnormal Liver disease
Tyrosine	Acidic	•Fine needles •Colorless, Yellow	Abnormal Liver disease
Sulfonamide	Acidic	•Needles, “wheat stacks”, sheaves, spheroids •Colorless, Yellow, Light Brown	Abnormal Medication
Radiographic dye	Acidic	•Flat needles or sheaves •Colorless	Abnormal Radiographic procedure