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Plasma or Serum Creatinine Concentration (Mass Concentration)

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

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

Quick summary

["A creatinine test checks kidney function by tracking waste removal from your blood."]

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

Key facts at a glance

LOINC
9976-2
Short code
QRS T-Amp L-I
Synonyms
QRS T-Amp L-I
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 This Test Matters

Creatinine is a byproduct of muscle breakdown and is normally filtered out of your blood by your kidneys. If your kidneys aren’t working well, creatinine levels can build up in your blood. This test helps doctors monitor kidney health, especially in people with conditions like diabetes, high blood pressure, or those taking certain medications that affect kidney function.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm or a blood sample taken from a finger prick. If you’re having a urine test for creatinine clearance (a related kidney function test), you’ll need to collect a 24-hour urine sample.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Higher than expected levels may suggest kidney problems, while very low levels could indicate muscle disorders or certain medical conditions.

Common Causes of Abnormal Results

Elevated creatinine levels may be due to kidney disease, dehydration, or conditions that reduce blood flow to the kidneys. Low levels might be linked to muscle wasting, liver disease, or certain genetic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is crucial for diagnosing and managing kidney disease, guiding treatment plans for chronic conditions, and ensuring medications are safely used when kidneys may be impaired.

Short name

Creatinine Level

Frequently asked questions

What triggers a creatinine test?
A creatinine test may be ordered if you have symptoms like swelling, fatigue, or changes in urine output, or if you have a history of kidney problems, diabetes, or high blood pressure. Doctors also use it to monitor kidney function during treatment for other conditions.
How often should I get a creatinine test?
The frequency depends on your health. People with kidney disease or risk factors may need tests every few months to a year. If you’re healthy, tests might be done less often, such as during routine check-ups or when symptoms arise.
Can diet or exercise affect creatinine levels?
Diet high in protein can temporarily raise creatinine levels, but it usually returns to normal after a few days. Exercise itself doesn’t change creatinine levels, but intense physical activity or muscle damage (like from injury) might temporarily affect results.
  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