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Serum Creatinine Concentration (Substance)

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

This test measures the amount of creatinine, a waste product from muscle breakdown, in your blood serum. It helps assess kidney function.

Quick summary

Your kidneys filter waste from blood; high creatinine may signal kidney problems.

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

Key facts at a glance

LOINC
106511-9
Short code
Mat ser scr Patient Ql Scn
Synonyms
Mat ser scr Patient Ql Scn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
3
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
screen
CPT
86140
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 metabolism that the kidneys remove from your blood. If your kidneys aren’t working well, creatinine builds up, which can affect your health. This test helps doctors check how well your kidneys are filtering waste.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel. Drink plenty of water the day before to help your kidneys process waste normally.

What the Results Mean

Results are compared to a general reference range based on age, sex, and overall health. Higher levels may indicate kidney issues, while lower levels could suggest dehydration or muscle loss. Your doctor will interpret results in the context of your medical history.

Common Causes of Abnormal Results

High creatinine levels may be linked to kidney disease, dehydration, heart failure, or conditions that reduce blood flow to the kidneys. Low levels might be due to dehydration, muscle wasting, or liver disease. Other factors, like certain medications or diet, can also influence results.

Reference range

Normal: <3.0 mg/LN/A

Specimen: serum

No special preparation required. CRP may be affected by acute illness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

How often do I need this test?
The frequency depends on your health. Healthy adults may get it once or twice a year, while people with kidney disease or risk factors (like diabetes or high blood pressure) may need it more often. Your doctor will schedule it based on your needs.
What if my results are out of range?
If your results are abnormal, your doctor will discuss possible causes and next steps, such as further testing or lifestyle changes. They may also monitor your kidneys closely if you have an underlying condition.
Can diet affect this test?
Yes, eating a high-protein diet or drinking less water before the test can raise creatinine levels. Avoiding excessive protein and staying hydrated the day before can help get more accurate 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