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Serum or Plasma 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. It helps assess how well your kidneys are filtering blood.

Quick summary

["A key indicator of kidney function and filtering efficiency."]

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

Key facts at a glance

LOINC
20490-9
Short code
EBV VCA IgG Titr Ser
Synonyms
EBV VCA IgG Titr Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82977
SNOMED
3110003
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 help doctors check if your kidneys are working properly. High levels may suggest kidney damage or disease, while low levels could indicate dehydration or other conditions affecting fluid balance.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. Stay hydrated unless instructed otherwise.

Common Causes of Abnormal Results

Elevated creatinine levels may result from kidney problems, dehydration, or muscle breakdown. Low levels could signal dehydration, overhydration, or certain metabolic disorders.

How Results Are Used in Care

Doctors use creatinine levels to monitor kidney function, guide treatment for conditions like diabetes or heart disease, and assess response to medications.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

Why did my doctor order this test?
Your doctor may have ordered this test to check kidney health, especially if you have symptoms like fatigue, swelling, or changes in urine output, or if you’re taking medications that affect kidneys.
What does a ‘normal’ result mean?
A ‘normal’ result doesn’t mean your kidneys are perfectly healthy—it just means your creatinine level falls within the typical range for your age, sex, and body size. Doctors interpret results in relation to your overall health.
Can diet affect creatinine levels?
Dietary protein intake can influence creatinine levels, but the test itself measures waste from muscle metabolism, not recent food. High-protein diets may temporarily raise levels, but this is usually short-term.
  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