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Serum or Plasma Creatinine Concentration (Substance Concentration)

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

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or plasma. It helps assess how well your kidneys are filtering blood.

Quick summary

["Kidney function depends on this test to detect early kidney problems."]

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

Key facts at a glance

LOINC
37066-8
Short code
XR Ribs-L 2V
Synonyms
XR Ribs-L 2V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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

Why It’s Done

Doctors may order this test to check for kidney disease, monitor kidney function in chronic conditions (like diabetes or high blood pressure), or evaluate symptoms such as swelling, fatigue, or changes in urine output. It’s also used before surgeries or procedures that may affect kidney function.

What to Expect

A small blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels. Results are typically available within 24–48 hours.

Normal vs. Abnormal Results

While reference ranges vary by lab, higher creatinine levels may suggest reduced kidney function, while lower levels could indicate dehydration or overhydration. Your doctor will interpret results in the context of your overall health.

What It Means for Your Health

Chronic kidney disease (CKD) can develop if creatinine levels rise over time, often without symptoms early on. Early detection helps manage conditions like diabetes or heart disease to slow progression.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are a key indicator of kidney function, but they’re not the only test. Your doctor may combine results with other markers (like blood urea nitrogen) or imaging to get a full picture.

Short name

Creatinine Level

Frequently asked questions

What causes creatinine levels to change?
Several factors can affect creatinine levels, including muscle mass (higher muscle = higher creatinine), dehydration, or certain medications. Kidney disease, heart failure, or liver problems can also influence results.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status. For example, people with diabetes or kidney disease may need it more frequently than others.
Can diet or exercise affect creatinine levels?
Diet high in protein can temporarily raise creatinine levels, but this usually returns to normal after a few days. Exercise itself doesn’t change creatinine levels, but intense workouts may temporarily alter hydration status.
  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