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Serum or Plasma Creatinine Concentration (Quantitative)

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 and detect early kidney problems."]

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

Key facts at a glance

LOINC
42936-5
Short code
ICS IgA Ser Ql IF
Synonyms
ICS IgA Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82784
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 to evaluate kidney health, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also used to monitor kidney function in people with diabetes, high blood pressure, or other conditions that can affect the kidneys.

What to Expect Before the Test

You can eat and drink normally before this test. If you’re having blood drawn, avoid eating or drinking for at least 8–12 hours before if instructed by your doctor (e.g., for some blood chemistry panels). No special preparation is needed for plasma/serum creatinine alone.

How the Test Is Performed

A healthcare provider will take a small blood sample from a vein in your arm using a needle. The sample is sent to a lab for analysis. For plasma, it may be drawn into a special tube to separate blood cells from fluid.

What the Results Mean

Higher-than-normal creatinine levels may indicate reduced kidney function, while lower levels could suggest dehydration or overhydration. Your doctor will interpret results in relation to your overall health and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your health status, such as whether you have kidney disease, diabetes, or other conditions that require monitoring. Regular follow-ups may be recommended if you’re at higher risk.
Can diet affect creatinine levels?
Dietary changes like high protein intake can temporarily raise creatinine levels, but this is usually short-term. Your doctor will consider overall health factors, not just diet, when reviewing results.
What if my results are abnormal?
If your creatinine level is elevated, your doctor may recommend further testing (like urine tests) or adjustments to medications that affect kidney function. Follow-up visits will help address concerns and guide treatment.
  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