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Serum Creatinine (Creatinine Level)

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 creatinine test helps check kidney function by measuring waste in your blood."]

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

Key facts at a glance

LOINC
8091-1
Short code
ENA RNP Ab Ser Ql
Synonyms
ENA RNP Ab 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
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 of your blood by your kidneys. High levels can indicate kidney problems, while low levels may suggest dehydration or muscle loss. This test is often used alongside other kidney function tests to monitor overall kidney health.

What to Expect Before the Test

You may not need special preparation. If you’re on a low-protein diet or have certain medications, your doctor may advise adjustments. Avoid strenuous exercise or heavy meals 12 hours before the test to ensure accurate results.

What Happens During the Test

A small blood sample is taken from a vein in your arm. It usually takes a few minutes, and you may feel a slight pinch. The sample is sent to a lab for analysis.

What the Results Mean

Results are compared to a reference range, but exact values can vary by lab. High creatinine levels may signal kidney issues, while very low levels might need further investigation. Your doctor will interpret results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated creatinine levels often indicate reduced kidney function, which can lead to complications like fluid buildup, electrolyte imbalances, or worsening of other health conditions. Regular monitoring helps detect kidney problems early and manage treatments effectively.

Short name

Creatinine

Frequently asked questions

What causes creatinine levels to be high?
High creatinine levels can result from kidney disease, dehydration, severe muscle damage, or conditions that reduce blood flow to the kidneys. Chronic kidney disease is the most common cause, but temporary factors like illness or medication use can also spike levels.
What causes creatinine levels to be low?
Low creatinine levels may occur with dehydration, muscle wasting (e.g., from malnutrition or illness), or certain medications that affect muscle metabolism. Rarely, it could indicate a metabolic disorder or overhydration, but further testing is needed to confirm.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status. People with kidney disease, diabetes, or heart conditions may need monitoring more frequently, while others may only require it periodically.
  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