Table 4 summarizes the characteristics of the more common types of abnormal crystals.
Table 4. Summary of Abnormal Crystals and their Characteristics.| Crystal | Color | Significance |
| Leucine | Yellow | Metabolism |
| Tyrosine | Colorless–yellow | Liver disease (rare) |
| Cystine | Colorless | Cysteine metabolism |
| Cholesterol | Colorless | Renal tubular disease |
| Bilirubin | Gold-orange | Increased bilirubin |
High doses of ampicillin, sulfonamide, or other drugs may also cause urine crystal formation. When unusual crystals are found in the urine specimen, it is important to check the patient's current medications.
