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Crystals in urine (urates, oxalates, phosphates)
Salt crystals in urinary sediment. Single ones are a normal variant; persistently many — a stone risk and a reason to review drinking and diet.
Other names: Urates, oxalates, phosphates, crystalsSection: UrinalysisSpecialist: Primary care physician, urologist, nephrologistSample: UrinePart of: Urinalysis
Updated: September 17, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortSingle salt crystals (urates, oxalates, phosphates) in urine are a normal variant: they precipitate in concentrated urine and with dietary features. What matters is a persistent abundance of crystals on repeat tests — a kidney stone risk and a reason to drink more and adjust the diet.
What this marker is
Urine always contains dissolved salts. When urine is concentrated or its acidity shifts, salts precipitate as crystals — the lab sees them in the sediment. The most common finds: urates (in acidic urine), oxalates (at any acidity) and phosphates (in alkaline urine).
A one-off crystal finding is not a disease but a reflection of recent diet and drinking. Kidney stone disease is considered when crystals are persistently abundant on repeat tests, especially with red blood cells and flank pain.
Reference ranges
Group
Reference range
Urates
single crystals per field — acceptable
Oxalates
single crystals per field — acceptable
Phosphates
single crystals in alkaline urine — acceptable
Persistently many crystals
a reason to assess stone risk (ultrasound, blood uric acid and calcium)
The crystal type depends on urine acidity and diet: urates — with excess meat and little drinking; oxalates — with excess spinach, sorrel, cocoa and vitamin C; phosphates — with alkaline urine and excess dairy. Ranges differ between laboratories.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
An approximate comparison with a typical range, not a diagnosis. Ranges differ between laboratories — use the one on your report; a doctor interprets the result.
When it is high or appears: possible causes
Too little drinkingConcentrated urine — salts precipitate as crystals.
Diet featuresExcess meat and offal (urates), spinach and cocoa (oxalates), dairy (phosphates).
Kidney stone diseasePersistent crystals are the “building material” of future stones.
Gout and hyperuricemiaExcess blood uric acid — many urates in urine.
These factors can shift the result without any disease — keep them in mind before a retest:
Little drinking the day beforeA meat-heavy day before (urates)Spinach, sorrel, chocolate (oxalates)High-dose vitamin C
How to prepare
A midstream sample of the first morning urine after cleaning the genital area, in a clean container, delivered to the lab within 1–2 hours. Details: Preparation: urine.
When a retest makes sense
A doubtful result is retested in 1–2 weeks with careful preparation. During treatment of a urinary tract infection, a follow-up is done 1–2 weeks after the course, as prescribed by the doctor.
Who usually reviews this result
An out-of-range result is usually reviewed by: Primary care physician, urologist, nephrologist. Bring your report and any previous results to the visit.
Names used on lab reports
Look for one of these names on your report: Crystals in urineUratesOxalatesPhosphatesUrinary crystals
Several markers on your report?
The app reads your whole report — this marker together with its neighbors, not one by one.
Not necessarily. Oxalates precipitate in everyone with excess sorrel, spinach, beets, cocoa and vitamin C and with little drinking. Stones are considered with persistent crystal abundance — then an ultrasound of kidneys and bladder is done.
Which foods cause urates?
Meat, offal, legumes, strong tea and cocoa — with their excess and little drinking, urates in urine increase. Persistent urates are a reason to check blood uric acid.
What to do about crystals in a child’s urine?
Most often it is enough to normalize drinking and diet and retest in 1–2 weeks. Persistent crystals are a reason for an ultrasound and a visit to the pediatrician or nephrologist.
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