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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 to assess kidney function.

Quick summary

["Helps check how well your kidneys are filtering waste from your blood."]

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

Key facts at a glance

LOINC
44540-3
Short code
HTLV II IgG Ser Ql IA
Synonyms
HTLV II IgG Ser Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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 Is Creatinine?

Creatinine is a byproduct of muscle breakdown that your kidneys filter out of your blood. High levels may indicate kidney problems, while low levels could suggest muscle weakness or other conditions. This test is often used alongside other kidney function tests to evaluate overall kidney health.

Why Is This Test Done?

Doctors may order this test to monitor kidney function, especially if you have symptoms like fatigue, swelling, frequent urination, or a history of kidney disease. It’s also used before surgeries, during pregnancy, or if you’re taking medications that can affect kidney function.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually causes only mild discomfort. If you’re on a low-protein diet or have had recent muscle injury, let your doctor know, as it may affect results.

What Happens During the Test?

A healthcare provider will clean your arm with an antiseptic, insert a needle into a vein, and collect a small blood sample. The process takes just a few minutes. You may feel a slight pinch or pressure, but the needle is only in for a brief moment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. If you have kidney disease, your doctor may recommend testing every few months. Otherwise, it’s often done once a year or as needed for monitoring.
Does diet affect creatinine levels?
Yes, diet can influence results. High-protein foods or muscle activity may temporarily raise creatinine levels. If you’re on a special diet, let your doctor know to avoid misleading results.
What if my results are abnormal?
If your creatinine level is high, your doctor may recommend further tests, like urine tests or imaging, to check kidney function. If low, they may investigate muscle issues or dehydration. Follow-up visits will help address any concerns.
  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