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Serum Creatinine (Substance Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood serum. It helps assess how well your kidneys are filtering blood.

Quick summary

["Your kidneys filter waste from blood; this test checks their function."]

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

Key facts at a glance

LOINC
85970-2
Short code
S pneum Da 1 Ab sp2 Ser-aCnc
Synonyms
S pneum Da 1 Ab sp2 Ser-aCnc
Category
coagulation
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 Is Done

Doctors may order a serum creatinine test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used to track kidney disease progression or response to treatment.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications (including supplements) or recent illnesses, as they can affect results. Avoid strenuous activity 24 hours before testing.

How the Test Works

A blood sample is drawn from a vein, usually in your arm. The lab analyzes the serum portion for creatinine levels using a specialized test method.

What the Results Mean

Results help determine kidney function by comparing it to your body’s muscle mass and other health factors. Abnormally high levels may indicate kidney problems, while low levels could suggest dehydration or muscle loss.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Serum creatinine is a key marker for kidney function. Elevated levels often signal impaired kidney filtration, which can lead to complications like fluid buildup, electrolyte imbalances, or worsening of chronic conditions like diabetes or hypertension. Regular monitoring helps detect kidney issues early, allowing for timely interventions.

Short name

Serum Creatinine

Frequently asked questions

What causes creatinine levels to change?
Several factors can influence creatinine levels, including muscle mass (higher muscle = higher creatinine), dehydration, certain medications (e.g., NSAIDs), or kidney disease. Age, sex, and ethnicity may also play a role in reference ranges.
How often should I get this test?
Your doctor will determine the frequency based on your health status. For stable conditions, tests may be done annually or as needed. If you have kidney disease, more frequent monitoring may be required.
Can diet or supplements affect this test?
Dietary changes (e.g., high-protein meals) or supplements (e.g., creatine) can temporarily alter creatinine levels. Avoid extreme dietary shifts before testing, and discuss supplements with your provider.
  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