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Urine Phosphate/Creatinine Ratio

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

This urine test measures phosphate relative to creatinine, helping assess how the kidneys handle phosphate.

Quick summary

["The ratio can help identify abnormal phosphate loss through the kidneys."]

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

Key facts at a glance

LOINC
11141-9
Short code
Phosphate/Creat Ur
Synonyms
Phosphate/Creat Ur
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 phosphate/creatinine ratio compares the amount of phosphate in urine with the amount of creatinine. Creatinine is used to account for how concentrated the urine sample is.

Why might I need this test?

This test may be used to evaluate kidney phosphate handling, especially in people with low blood phosphate, kidney disease, or symptoms suggesting a phosphate-handling disorder.

How is the test performed?

A urine sample is tested to determine its phosphate and creatinine concentrations, and the results are used to calculate the ratio. The sample may be a single collection or part of a timed collection, depending on the order.

How do I prepare for the test?

Follow your clinician's instructions about urine collection and timing. If a first-morning or timed sample is requested, collect it exactly as directed and tell the healthcare team if you recently changed medications or diet.

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

Phosphate/Creatinine Ratio

Frequently asked questions

Does this test measure blood phosphate?
No. This test uses urine to measure phosphate relative to creatinine. Your clinician may order blood phosphate and kidney tests at the same time for interpretation.
Why is creatinine included in the result?
Urine concentration can vary from sample to sample. Creatinine helps normalize the phosphate measurement so that results from different samples are easier to compare.
What could cause an abnormal ratio?
Possible causes include kidney disease, medications that alter phosphate handling, low phosphate intake, or conditions that cause the body to lose phosphate through the kidneys.
  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