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Serum Creatinine (Creatinine Level)

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["A creatinine test helps check kidney function by measuring waste in your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
97158-0
Short code
CK8 Ag tiss Ql ImStn
Synonyms
CK8 Ag tiss Ql ImStn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-stain
CPT
82553
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. High levels can indicate kidney problems, while low levels might suggest dehydration or muscle loss. Your doctor may order this test to monitor kidney health, especially if you have conditions like diabetes or high blood pressure.

What to Expect Before the Test

You may be asked to fast for 8–12 hours before the test, but this is not always required. Drink plenty of water the day before to ensure your kidneys are functioning normally. Avoid strenuous exercise or heavy meals before testing.

How the Test Works

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab where creatinine levels are measured using a specialized test method. Results help determine how well your kidneys are working to remove waste from your blood.

Possible Results and Next Steps

If your creatinine levels are higher than expected, your doctor may recommend further kidney function tests or adjustments to your medications. If levels are low, they may investigate potential causes like dehydration or muscle conditions. Follow-up visits will depend on your overall health and test results.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine

Frequently asked questions

What causes elevated creatinine levels?
Elevated creatinine levels can result from kidney disease, dehydration, severe muscle damage, or conditions that reduce blood flow to the kidneys. Chronic kidney disease, heart failure, or certain medications may also contribute.
What causes low creatinine levels?
Low creatinine levels may occur with dehydration, muscle atrophy (loss of muscle mass), liver disease, or certain genetic conditions. They can sometimes indicate overhydration or underactive kidneys, but further testing is needed to confirm.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, current medications, and any kidney-related conditions. Regular monitoring may be recommended if you have diabetes, high blood pressure, or a history of kidney issues.
  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 17, 2026. · Read our editorial policy