Crystals in Urine Show Up in Nearly 1 in 3 Samples, and Most Mean Nothing
Somewhere between 20% and 30% of outpatient urine samples contain crystals. If your lab report flags crystalluria, the odds are strongly in favor of it being a normal, harmless finding. But a handful of crystal types, or crystals that keep showing up in large amounts, tell a genuinely important story about stone risk, infection, metabolic disease, or drug toxicity. The difference between "ignore it" and "investigate now" comes down to which crystals, how many, and how often. A single urinalysis showing a few calcium oxalate crystals after a dehydrated morning is routine. Persistent hexagonal cystine crystals are a different situation entirely. Knowing the distinction matters more than most people realize.