URINALYSIS - CRYSTALS

Amorphous urates

Normal crystal found in acid or neutral urine

Irregular granules

form pink precipitate at bottom of tube, dissolve by warming to 60 degrees C.

Uric acid

Normal crystal found in acid or neutral urine

Pleomorphic. 4-sided, 6-sided, star-shaped, rosettes, spears, plates. Colorless, red-brown, or yellow.

Birefringent, polarizes light

Calcium oxalate

Normal crystal found in neutral or acid urine

Octahedral envelope form is most common. Also dumbbell and ovoid forms.

Most common constituent of renal calculi.

Amorphous phosphates

Normal crystal found in alkaline urine

irregular granules

form white precipitate at bottom of tube, dissolve with 2% acetic acid

Triple phosphate

Normal crystal found in alkaline urine

"coffin-lid" crystal

Ammonium biurate

Normal crystal found in alkaline urine

Yellow-brown "thorn apples" and spheres

seen in old specimens

Calcium phosphate

Normal crystal found in alkaline urine

needles, rosettes, "pointing finger"

only needle form seen in alkaline urine

Calcium carbonate

Normal crystal found in alkaline urine

colorless dumbbells or aggregates

Leucine

Abnormal crystal

Yellow, oily-looking spheres. Radial and concentric striations.

Seen in severe liver disease and often seen with tyrosine

Tyrosine

Abnormal crystal

Fine yellow needles in sheaves or rosettes.

Seen in severe liver disease and often seen with leucine

Cystine

Abnormal crystal

Hexagonal

Seen in cystinuria; must differentiate from uric acid (doesn't polarize light)

Cholesterol

Abnormal crystal

Flat plates. Notched out corners. "Stair steps"

Seen in nephrotic syndrome and are birefringent

Bilirubin

Abnormal crystal

Yellowish-brown needles, plates, granules.

Seen in liver disease.