Skip to content

Serum Creatinine (with optional 24-hour urine collection for creatinine clearance calculation)

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

["Kidney function and fluid balance depend on this test."]

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

Key facts at a glance

LOINC
85826-6
Short code
OXA24
Synonyms
blaOXA-24-like Islt/Spm Ql
Category
chemistry
Sample
serum
Container
Sterile, leak-proof container; appropriate transport medium (e.g., Amies or Stuart transport medium) for culture isolates; sterile cryovial for purified DNA/bacterial isolates
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
molgen
CPT
87798 (unlisted infectious agent detection by nucleic acid, amplified probe technique) or 87150 (culture identification by molecular methods) depending on laboratory billing practices; additional CPT 87186 for susceptibility testing if applicable
SNOMED
122450008 | Bacterial resistance gene identification (procedure)|; 419329009 | Detection of carbapenemase-producing organism (procedure)|
Specimen volume
Variable depending on specimen source: pure bacterial isolate (single colony) or 1-2 mL fluid sample (blood, sterile body fluid). Minimum 200 µL for nucleic acid extraction.
Stability
Specimen stability varies by sample type. Bacterial isolates: stable at 2-8°C for up to 7 days; at room temperature (20-25°C) for up to 2 days. DNA extracts: stable at 2-8°C for 7 days; -20°C or -80°C for long-term storage (≥1 year). Avoid repeated freeze-thaw cycles.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why Your Kidneys Matter

Creatinine is a byproduct of muscle breakdown and is filtered out of your blood by your kidneys. High levels can signal kidney problems, while low levels might indicate dehydration or other conditions. Your doctor may also use this test to check how well your kidneys are working over time.

What to Expect During the Test

For a blood test, a small sample of blood is taken from a vein, usually in your arm. For a 24-hour urine test, you’ll collect all urine over a full day. Follow your healthcare provider’s instructions carefully to ensure accurate results.

Factors That Can Affect Results

Several factors can influence creatinine levels, including muscle mass, diet (especially protein intake), hydration status, and certain medications. Dehydration, muscle injury, or conditions like heart failure can raise levels, while overhydration or certain liver/kidney diseases may lower them.

Common Reasons for Testing

Your doctor may order this test to check for kidney disease, monitor kidney function after treatment, evaluate symptoms like swelling, fatigue, or changes in urine, or assess overall health in people at higher risk for kidney problems.

Reference range

Negative (blaOXA-24-like gene not detected). Positive indicates presence of the carbapenem-resistance gene.N/A

Specimen: serum

No special patient preparation required. However, specimen collection should occur prior to initiation of antimicrobial therapy when possible to maximize pathogen and resistance gene detection. Standard aseptic technique for sample collection is essential.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are a key indicator of kidney function. Elevated levels suggest impaired filtration, which can lead to long-term kidney damage if untreated. Doctors use these results alongside other tests to diagnose, monitor, or guide treatment for conditions like chronic kidney disease (CKD), acute kidney injury, or other systemic illnesses.

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. People with kidney disease or risk factors (like diabetes or high blood pressure) may need tests more often, while healthy individuals might only need baseline checks or follow-ups if symptoms arise.
What if my results are abnormal?
If your results are higher than expected, your doctor may recommend further tests, adjustments to medications, or lifestyle changes to support kidney health. If levels are low, they could investigate causes like dehydration or muscle loss.
Can diet or exercise affect creatinine levels?
Yes! High-protein diets or intense exercise can temporarily raise creatinine levels. Staying hydrated and balancing protein intake can help maintain stable results. Always discuss dietary changes with your healthcare provider.
  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