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Urine Phosphate/Creatinine Ratio

Published: August 9, 2026Updated: August 17, 2026

Measures the amount of phosphate relative to creatinine in urine, helping assess phosphate levels and how the kidneys handle phosphate.

Quick summary

["This urine test helps evaluate phosphate balance and possible kidney-related phosphate loss."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
34354-1
Short code
Phosphate/Creat Ur-sRto
Synonyms
Phosphate/Creat Ur-sRto
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
2.5
Ref high
4.5
Critical range
1 N/A – —
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84100
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

The urine phosphate/creatinine ratio compares the amount of phosphate in your urine with the amount of creatinine. Creatinine is used to help account for how concentrated or dilute the urine sample is.

Why might I need this test?

This test may be used to evaluate phosphate balance, especially in people with low blood phosphate, bone disease, vitamin D deficiency, kidney disease, or a condition that causes the kidneys to lose too much phosphate.

How is the test performed?

A urine sample is tested to measure its phosphate and creatinine levels. The laboratory then calculates the phosphate-to-creatinine ratio. Your clinician may request a single sample or urine collected over a specified period.

How do I prepare for the test?

Follow your clinician's instructions about the type and timing of urine collection. If a 24-hour collection is requested, collect all urine for the full period and store it as directed. The sample may need to be kept chilled.

Reference range

Adult: 2.5-4.5 mg/dLN/A

Specimen: urine

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine phosphate/creatinine ratio

Frequently asked questions

Is this the same as a blood phosphate test?
No. This test measures phosphate relative to creatinine in urine, while a blood phosphate test measures the phosphate concentration in blood.
Why is creatinine included in the result?
Creatinine helps adjust for urine concentration, so the phosphate result is less affected by whether the sample is very dilute or concentrated.
Does an abnormal result diagnose a specific condition?
No. An abnormal ratio can have several causes and is usually interpreted together with blood tests, symptoms, and other medical history.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy