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Serum or Plasma Creatinine Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 16, 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 key indicator of kidney function and overall health."]

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

Key facts at a glance

LOINC
9927-5
Short code
Q wave Dpth L-AVR
Synonyms
Q wave Dpth L-AVR
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
CPT
85610
SNOMED
396252006
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 naturally filtered by your kidneys. High levels can signal impaired kidney function, while low levels may indicate dehydration or other conditions. This test is often used alongside other measures to monitor kidney health, especially in people with diabetes, hypertension, or a history of kidney disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader panel. Drink plenty of water the day before to ensure accurate results. Avoid heavy exercise or strenuous activity, as it could temporarily raise creatinine levels.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. The blood sample is then sent to a lab for analysis. The test typically takes a few minutes, and you may feel slight discomfort or bruising at the injection site.

Possible Results and Interpretation

Results are compared to a reference range specific to your age, sex, and overall health. While exact values vary, consistently high or low levels may prompt further investigation, such as additional kidney function tests or imaging.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What causes creatinine levels to be high?
High creatinine levels can result from kidney disease, dehydration, severe muscle damage (e.g., from injury or illness), or conditions that restrict blood flow to the kidneys. Chronic kidney disease is the most common cause, but temporary factors like intense exercise or illness can also spike levels.
What causes creatinine levels to be low?
Low creatinine levels may suggest dehydration, low muscle mass, or certain medical conditions that affect muscle metabolism. Rarely, they could indicate overhydration or a rare genetic disorder. Your doctor will consider your medical history and other test results to determine the cause.
How often should I get this test?
Your doctor may recommend this test periodically if you have kidney-related conditions, diabetes, high blood pressure, or a family history of kidney disease. Frequency depends on your individual health needs, such as whether you’re taking medications that affect kidney function or if you have symptoms like fatigue or swelling.
  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