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Protein-to-Creatinine Ratio, Serum/Plasma

Published: August 9, 2026Updated: August 16, 2026

A calculated blood test that compares total protein with creatinine, which can help evaluate protein levels in relation to kidney function.

Quick summary

["This ratio provides context about protein levels and kidney function, but results must be interpreted with other tests."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
30154-9
Short code
Prot/Creat SerPl
Synonyms
Prot/Creat SerPl
Category
kidney
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

This test measures total protein and creatinine in a blood sample and calculates the amount of protein for each amount of creatinine. It is sometimes used to help interpret protein levels together with kidney function.

Why might I need this test?

Your clinician may order it when evaluating kidney function, protein-related conditions, or an abnormal urine protein result. It is often interpreted alongside urine tests and other blood tests.

How is the test performed?

A blood sample is collected, usually by a venipuncture. The laboratory measures protein and creatinine and calculates the protein-to-creatinine ratio.

How do I prepare for the test?

No special preparation is usually required. Tell your clinician if you are pregnant, have a bleeding disorder, or are taking blood thinners, because these factors may affect the blood draw.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Protein/Creatinine Ratio

Frequently asked questions

Is this the same as a urine protein-to-creatinine ratio?
No. The test described here uses serum or plasma, whereas a urine protein-to-creatinine ratio measures both substances in urine. Check the specimen listed on your laboratory report if you are unsure.
Does an abnormal result mean I have kidney disease?
Not necessarily. Kidney disease is one of several possible explanations, and hydration, muscle mass, liver conditions, and other factors can also affect the ratio.
Do I need to fast before this test?
Fasting is generally not required, but follow any specific instructions from your clinician or laboratory. Your result may be interpreted differently if you are dehydrated or ill.
  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 16, 2026. · Read our editorial policy