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Serum or Plasma Creatinine Concentration (Standard Method)

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

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

Quick summary

["Kidney function depends on this test to detect early kidney problems."]

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

Key facts at a glance

LOINC
18510-8
Short code
ST Seg axis HP
Synonyms
ST Seg axis HP
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 Is This Test Done?

Your doctor may order this test if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used to monitor kidney health in people with conditions like diabetes or high blood pressure.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before a blood draw if your doctor specifies it. Drink plenty of water the day before if you’re having a urine test.

How the Test Works

A small sample of blood or plasma is taken from a vein in your arm. For urine tests, you may collect a sample over 24 hours or provide a single sample. The lab uses a standard method to measure creatinine levels.

Possible Results & Interpretation

Results are compared to a reference range based on age, sex, and health. Low levels may suggest kidney issues or muscle disorders, while very high levels could indicate kidney disease or dehydration.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What Causes Abnormal Results?
High creatinine levels can result from kidney disease, dehydration, or muscle breakdown. Low levels may occur with poor kidney function, liver disease, or certain medications.
How Often Should I Get This Test?
Your doctor will determine frequency based on your health. People with kidney issues may need tests every few months, while others may only need it once yearly.
Can I Eat or Drink Normally Before the Test?
For blood/plasma tests, fasting may be required, but always follow your doctor’s instructions. For urine tests, avoid excessive fluids unless specified otherwise.
  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