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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

["A creatinine test helps check kidney function by measuring waste removal efficiency."]

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

Key facts at a glance

LOINC
45148-4
Short code
OmpC IgA Ser Ql
Synonyms
OmpC IgA Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 Your Kidneys Matter

Kidneys filter waste and excess substances from your blood, including creatinine. If your kidneys aren’t working well, creatinine levels can build up, which may indicate kidney problems. This test is often used alongside other kidney function tests to monitor overall kidney health.

What to Expect Before the Test

You may be asked to fast for 8–12 hours before the test, but this isn’t always required. Bring any medications you’re currently taking, as some (like certain pain relievers) can affect results. Avoid heavy exercise or strenuous activity the day before.

How the Test Works

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure creatinine levels using a standard method, often involving automated chemistry techniques.

Common Causes of Abnormal Results

High creatinine levels may suggest kidney disease, dehydration, or conditions that increase muscle breakdown (e.g., severe illness, burns). Low levels could indicate overhydration or rare metabolic disorders. Your doctor will consider your overall health and other test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

What does a creatinine test tell me about my kidneys?
It provides a snapshot of how well your kidneys are filtering waste from your blood. High levels may signal reduced kidney function, while low levels could raise questions about hydration status or other metabolic factors. Your doctor will interpret results in the context of your medical history and other tests.
Can diet or medications affect creatinine levels?
Yes, certain foods (like red meat) and medications (e.g., NSAIDs, certain diuretics) can influence creatinine levels. Avoiding high-protein foods or certain supplements for a few days before testing may help stabilize results. Always follow your doctor’s instructions.
How often should I get a creatinine test?
Frequency depends on your health status. People with kidney disease or risk factors (e.g., diabetes, hypertension) may need tests every few months to a year. Regular screenings are also recommended for those with a family history of kidney problems or certain genetic conditions.
  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