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Serum Creatinine (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 how well your kidneys are filtering blood.

Quick summary

["Your kidneys filter waste from your blood, and creatinine is one key marker of kidney function."]

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

Key facts at a glance

LOINC
110050-2
Short code
C trach D+K IgA Msmt Ser
Synonyms
C trach D+K IgA Msmt Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Matters

Creatinine levels can indicate how well your kidneys are working. High levels may suggest kidney damage or disease, while low levels could indicate dehydration or other conditions affecting muscle metabolism.

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, and you’ll likely feel a brief pinch. If you’re dehydrated, your creatinine level might appear higher than usual, so staying well-hydrated the day before can help.

Common Causes of Abnormal Results

Elevated creatinine levels can be caused by kidney problems, muscle disorders, or dehydration. Lower levels might suggest muscle loss, overhydration, or certain liver conditions. Always discuss any changes with your healthcare provider.

What Your Results Mean

Your results will be compared to a general reference range, but individual results can vary based on age, sex, and overall health. Your doctor will interpret these results in the context of your medical history and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine

Frequently asked questions

How often will I need this test?
This test is often checked regularly if you have kidney disease, diabetes, high blood pressure, or other conditions that put you at risk. Your doctor may order it less frequently if you’re healthy and have no risk factors.
What if my results are out of the normal range?
If your creatinine level is higher than expected, your doctor may recommend further kidney function tests, such as a glomerular filtration rate (GFR) test, to understand the cause. If it’s lower, they might investigate other possible reasons, like muscle loss or fluid overload.
Can diet or exercise affect my creatinine levels?
Yes, diet high in protein can temporarily raise creatinine levels, as muscle breakdown increases. Staying hydrated and eating a balanced diet can help maintain stable levels. Exercise itself doesn’t directly change creatinine, but it may indirectly affect kidney function over time.
  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