There are many things that can cause crystals to form in urine. They include:
- Dehydration (not drinking enough water).
- Eating large amounts of certain foods, including protein, salt, fruits and vegetables.
- Medications such as amoxicillin, acyclovir, sulfonamides, atazanavir and methotrexoate.
- Urinary tract infections.
- Ethylene glycol poisoning.
- Having tumor lysis syndrome, which is caused by the death of a large number of cancer cells. This may happen as a result of cancer treatment.