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Plasma or Serum Creatinine Concentration (Mass Concentration)

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 kidney function by checking how well your kidneys filter blood.

Quick summary

["A creatinine test helps determine if your kidneys are working properly."]

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

Key facts at a glance

LOINC
9901-0
Short code
P wave dur L-AVF
Synonyms
P wave dur L-AVF
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 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.

What to Expect Before the Test

You may have this test done by drawing blood from a vein in your arm or collecting a urine sample. If blood is drawn, you might feel a small pinch, but it usually doesn’t cause discomfort. No special preparation is needed unless your doctor instructs otherwise.

What the Results Mean

Higher than expected levels may suggest kidney problems, while lower levels could indicate dehydration or muscle loss. Your doctor will compare your results to your overall health and other tests to interpret them accurately.

Common Causes of Abnormal Results

Elevated creatinine levels can be caused by kidney disease, dehydration, severe muscle damage, or certain medications. Lower levels might be due to overhydration, liver disease, or conditions that reduce muscle mass.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

What triggers a creatinine test?
Your doctor may order a creatinine test if you have symptoms like swelling, fatigue, or changes in urine output, or if you have a condition like diabetes or high blood pressure that increases kidney risk. It may also be part of routine check-ups or before certain treatments.
How long does it take to get results?
Results are typically available within a few days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
Can diet affect creatinine levels?
Dietary changes like eating a lot of red meat or protein-rich foods can temporarily raise creatinine levels, but your doctor will consider overall health factors, not just diet, when interpreting results.
  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