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Serum or Plasma Creatinine Concentration (Qualitative or Quantitative Probe-Based Test)

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

A creatinine test helps check kidney function by measuring waste product levels in your blood.

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

Key facts at a glance

LOINC
76577-6
Short code
S aureus sau3AI Swab Ql NAA+probe
Synonyms
S aureus sau3AI Swab Ql NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 Is Done

Your doctor may order this test if you have symptoms like swelling, frequent urination, fatigue, or if they suspect kidney problems. It’s also used to monitor kidney health in people with diabetes, high blood pressure, or other chronic conditions.

What to Expect Before the Test

No special preparation is needed unless instructed. You may be asked to fast for 8–12 hours before a blood test, but for urine or plasma samples, hydration and diet may not affect results. Avoid strenuous activity 24 hours before testing.

How the Test Is Performed

For blood/plasma: A healthcare provider will draw blood from a vein in your arm. For urine: You’ll collect a sample in a sterile container. Plasma samples may be processed from whole blood or directly from plasma tubes.

What the Results Mean

Results are compared to general reference ranges, but individual ranges can vary by lab. High levels may indicate kidney issues, while very low levels could suggest muscle disorders or dehydration. Your doctor will interpret results in the context of your health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Chronically elevated creatinine levels often signal impaired kidney function, requiring further evaluation (e.g., kidney biopsy, imaging). Low levels may warrant follow-up to rule out muscle breakdown or fluid loss. This test is a key part of monitoring kidney disease progression and response to treatment.

Short name

Creatinine Level Check

Frequently asked questions

What causes creatinine levels to change?
Creatinine levels can rise due to kidney disease, dehydration, severe muscle damage, or certain medications. They may drop with overhydration, muscle loss, or rare metabolic conditions. Always discuss symptoms with your doctor.
How often should I get this test?
Frequency depends on your health. People with kidney disease may need tests every few months. Others with risk factors (e.g., diabetes, hypertension) may get baseline tests once or twice a year. Follow your doctor’s schedule.
Can diet or exercise affect creatinine levels?
Dietary protein intake may slightly influence creatinine levels, but the effect is small. Exercise generally doesn’t change levels unless it causes muscle damage. Hydration and kidney health are more impactful.
  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