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Serum Creatinine Concentration (Mass Concentration)

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

This test measures the amount of creatinine, a waste product from muscle breakdown, in your serum. It helps assess how well your kidneys are filtering blood.

Quick summary

["Kidney function check: creatinine helps detect early kidney problems."]

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

Key facts at a glance

LOINC
33400-3
Short code
N men sg B+E coli K1 Ag Ser Ql LA
Synonyms
N men sg B+E coli K1 Ag Ser Ql LA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
la
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 your kidneys filter out of your blood. High levels can signal kidney damage or dysfunction, even before other symptoms appear. Your doctor may order this test to monitor kidney health, especially if you have conditions like diabetes, high blood pressure, or a family history of kidney disease.

How the Test Works

A small blood sample is taken from your arm. The lab uses a specialized method (likely enzymatic or chemiluminescent immunoassay) to measure creatinine levels in your serum. Results are compared to a reference range to determine if your kidneys are working as expected.

What to Expect Before the Test

No special preparation is needed for this test. You may eat and drink normally, but inform your doctor about any medications you’re taking, as some (like certain pain relievers or diuretics) can affect kidney function.

What to Expect After the Test

The blood draw usually takes a few minutes. You may feel slight discomfort, but it’s temporary. You can resume your normal activities right after. Your results will be reviewed by a healthcare provider to guide further care if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

What does a high or low creatinine level mean?
High creatinine levels may indicate reduced kidney function, fluid overload, or dehydration. Low levels could suggest overhydration, liver disease, or muscle wasting. Your doctor will interpret results in the context of your overall health and other tests.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and risk factors. Regular monitoring may be recommended if you have chronic conditions like diabetes or kidney disease.
Can diet affect creatinine levels?
Yes, diet can influence creatinine levels. High-protein diets may temporarily increase levels, while dehydration can raise them. Staying hydrated and following your doctor’s dietary advice is important.
  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