Skip to content

Plasma or Serum Creatinine (Creatinine 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 simple blood test."]

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

Key facts at a glance

LOINC
77486-9
Short code
Deprecated Hind+Mid ft-R XR AP+Lat
Synonyms
Deprecated Hind+Mid ft-R XR AP+Lat
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 Is This Test Done?

Your doctor may order this test to check kidney function, diagnose kidney disease, or monitor conditions like diabetes or heart disease that can affect kidney health. It’s often used alongside other tests like blood urea nitrogen (BUN) to evaluate kidney performance.

What Does a High or Low Level Mean?

High levels may indicate poor kidney function, dehydration, or conditions like severe muscle breakdown. Low levels can sometimes suggest overhydration or liver disease, though this is less common. Results are interpreted in the context of your overall health and other tests.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where creatinine is measured using an automated method, often enzymatic or spectrophotometric, to determine its concentration in your blood or plasma.

What Should You Do Before the Test?

Avoid strenuous exercise or heavy meals 24 hours before the test to ensure accurate results. If you’re on certain medications (like NSAIDs or diuretics), discuss this with your doctor, as they may affect kidney function and test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are a key marker for kidney function because they reflect how well your kidneys remove waste products from your blood. Chronic kidney disease (CKD) is often detected early through elevated creatinine levels, even before symptoms appear. Regular monitoring helps manage conditions like diabetes or hypertension that can strain kidney function over time.

Short name

Creatinine Level

Frequently asked questions

How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will discuss the findings with you during a follow-up visit.
Can diet or exercise affect my creatinine levels?
Dietary protein intake and muscle mass influence creatinine levels, but moderate exercise or a balanced diet usually won’t cause significant changes. Avoid extreme protein restriction or excessive muscle-building activities before testing, as they may alter results.
What if my creatinine level is abnormal?
If your results are outside the expected range, your doctor may recommend further testing, such as additional kidney function tests (e.g., glomerular filtration rate, GFR), or adjustments to your treatment plan. Follow-up visits will help address any concerns and guide next steps.
  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