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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 urine. It helps assess how well your kidneys are filtering blood.

Quick summary

["A creatinine test helps check kidney function and detect early kidney problems."]

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

Key facts at a glance

LOINC
104562-4
Short code
Own or rent your home
Synonyms
Own or rent your home
Category
chemistry
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 Matters

Creatinine is a byproduct of muscle breakdown and is normally filtered out by your kidneys. If your kidneys aren’t working well, creatinine builds up in your blood. This test helps doctors monitor kidney health, especially in people with diabetes, high blood pressure, or other conditions that can affect the kidneys.

How the Test Works

Your blood or urine sample is sent to a lab where it’s analyzed using a standard method, often involving chemical reactions or specialized equipment to measure creatinine levels precisely.

What to Expect Before the Test

No special preparation is usually needed for a blood creatinine test. For a 24-hour urine test, you’ll need to collect all urine over a full day, starting after your first morning pee. Follow your doctor’s instructions carefully to ensure accurate results.

What the Results Mean

Higher than expected creatinine levels may indicate poor kidney function, while lower levels could suggest overhydration or other conditions. Your doctor will interpret the results in relation to your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What causes creatinine levels to change?
Several factors can influence creatinine levels, including muscle mass (higher muscle mass can lead to higher levels), dehydration, certain medications, or kidney disease. If you’ve had recent changes in activity, diet, or medications, let your doctor know.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition. For example, people with kidney disease may need tests more frequently, while others with stable conditions might only need occasional checks.
Can diet affect creatinine levels?
Dietary changes like eating more protein can temporarily raise creatinine levels, but this usually returns to normal after a few days. Always discuss dietary adjustments with your healthcare provider before making significant changes.
  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