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Serum Creatinine (Creatinine Level)

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

["Kidney function check: creatinine helps doctors see if your kidneys are working properly."]

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

Key facts at a glance

LOINC
18491-1
Short code
C trach G+F+K IgG Titr Ser IF
Synonyms
C trach G+F+K IgG Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82977
SNOMED
3110003
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

What Does Creatinine Tell Us?

Creatinine is a byproduct of muscle breakdown and is normally filtered out of your blood by your kidneys. High levels can indicate kidney problems, while low levels may suggest dehydration or muscle wasting. This test is often used alongside other kidney function tests to diagnose and monitor conditions like chronic kidney disease.

Why Is This Test Done?

Doctors order creatinine tests to evaluate kidney function, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before surgeries, during pregnancy, or when managing conditions like diabetes or heart disease.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels. No special preparation is needed, but fasting may be advised in some cases for related tests.

What Are Common Results?

Results are compared to a general reference range, but individual results can vary based on factors like age, sex, and muscle mass. High levels may need further investigation to rule out kidney issues or other conditions.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine

Frequently asked questions

What Does a High Creatinine Level Mean?
A high creatinine level often signals impaired kidney function, as your kidneys struggle to remove waste products from your blood. This can be an early sign of chronic kidney disease or acute kidney injury. Doctors may recommend additional tests or adjustments to your treatment plan if levels are elevated.
What Does a Low Creatinine Level Mean?
Low creatinine levels may suggest dehydration, low muscle mass, or liver disease, which can affect muscle breakdown. In some cases, it might also indicate overhydration or certain metabolic conditions. Your doctor will consider other factors to interpret results accurately.
How Often Should I Get This Test?
Your doctor will determine how often you need this test based on your health history, current conditions, and treatment plan. Regular monitoring may be recommended if you have kidney disease, diabetes, or heart conditions.
  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