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Plasma Creatinine (Creatinine Concentration)

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

This test measures the level of creatinine, a waste product from muscle metabolism, in your blood plasma. It helps assess kidney function.

Quick summary

["Your kidneys filter waste like creatinine from your blood; high levels may signal kidney problems."]

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

Key facts at a glance

LOINC
47923-8
Short code
GH sp4 p chal SerPl-aCnc
Synonyms
GH sp4 p chal SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 by your kidneys. If your kidneys aren’t working well, creatinine builds up in your blood. This test helps doctors check how well your kidneys are doing and monitor kidney disease or other conditions that may affect them.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm or vein to draw a blood sample. If you’re on a low-protein diet or have certain medications, your doctor may advise adjustments.

What the Results Mean

Results are compared to a reference range based on age, sex, and overall health. Higher than expected levels may indicate kidney problems, while lower levels could suggest dehydration or muscle loss. Your doctor will discuss your specific results with you.

Common Conditions Monitored

This test is often used to diagnose or monitor kidney disease, including chronic kidney disease (CKD), acute kidney injury (AKI), and conditions like diabetes or heart failure that can affect kidney function.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What causes high creatinine levels?
High creatinine levels can result from kidney problems, such as chronic kidney disease, acute kidney injury, or blockages in the urinary tract. Other factors, like severe dehydration, muscle disorders, or certain medications, may also raise levels temporarily.
What causes low creatinine levels?
Low creatinine levels may occur if you have very little muscle mass, are severely dehydrated, or have certain metabolic conditions. Rarely, it can also be due to overhydration or certain genetic factors.
Can diet affect creatinine levels?
Yes, diet can influence creatinine levels. Eating a high-protein diet may temporarily increase creatinine, while a low-protein diet could lower it. Your doctor may recommend dietary adjustments if needed, especially if you have kidney concerns.
  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