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Plasma or serum concentration of creatinine

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 kidney function.

Quick summary

["A creatinine test helps check how well your kidneys are filtering blood."]

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

Key facts at a glance

LOINC
49946-7
Short code
GH 11 PM SerPl-aCnc
Synonyms
GH 11 PM 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 levels can build up in your blood. This test helps doctors monitor kidney health, especially in people with diabetes, high blood pressure, or other conditions that may affect the kidneys.

What to Expect Before the Test

You may be asked to fast for 8–12 hours before the test, but this isn’t always required. Bring any medications you’re currently taking, as some (like certain pain relievers) can affect results. Avoid strenuous activity the day before.

How the Test Works

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine concentration. Results are compared to a baseline or reference range to determine kidney function.

What Your Results Mean

Higher-than-normal levels may indicate kidney problems, while lower levels could suggest muscle loss or liver disease. Your doctor will interpret results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

Why might my doctor order this test?
Your doctor may order a creatinine test to check for kidney disease, monitor chronic conditions like diabetes or heart disease, or evaluate symptoms such as swelling, fatigue, or changes in urine output. It’s also used to assess how well medications are being processed by your kidneys.
What if my results are abnormal?
If your creatinine levels are higher than expected, your doctor may recommend further tests, like a urine test or imaging, to investigate kidney function. If levels are low, they might look for other causes like malnutrition or liver issues.
How often should I get this test?
Frequency depends on your health. People with kidney disease or risk factors may need tests every few months to a year. Your doctor will let you know if you need regular monitoring.
  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