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Serum or Plasma Creatinine Concentration (Quantitative)

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 tracking how well your body removes waste products."]

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

Key facts at a glance

LOINC
85823-3
Short code
GESCR
Synonyms
blaGES Islt/Spm Ql
Category
chemistry
Sample
serum
Container
Sterile, leak-proof container; for serum, use serum separator tube (SST) or red-top vacutainer tube. For bacterial isolates, use appropriate transport medium or culture plate.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
molgen
CPT
87153 (Culture, typing; identification of nucleic acid sequence by PCR or other molecular methods, each isolate). Alternatively, 87798 (Amplified probe technique, each organism) may apply depending on laboratory billing structure.
SNOMED
122450008 | Microbial culture, quantitative (procedure)| or 258660001 | Polymerase chain reaction procedure (procedure)|
Specimen volume
1-2 mL serum; or pure bacterial isolate from culture on appropriate media
Stability
Serum: Room temperature 24 hours; Refrigerated (2-8°C) 7 days; Frozen (-20°C or below) up to 30 days. Bacterial DNA extracts: -20°C to -80°C for long-term storage. Avoid repeated freeze-thaw cycles.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why This Test Is Done

Doctors may order a creatinine test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used before certain medications or procedures to ensure your kidneys are functioning properly.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before a blood test. For a urine test, you might collect a sample over 24 hours. Hydration can affect results, so drink as usual unless instructed otherwise.

What the Results Mean

Higher than expected levels may indicate poor kidney function, while lower levels could suggest overhydration or muscle breakdown. Results are compared to your age, sex, and overall health for interpretation.

Common Causes of Abnormal Results

Kidney disease, dehydration, heart failure, or certain medications can raise creatinine. Low levels may result from fluid overload or conditions like liver disease. Always discuss results with your healthcare provider.

Reference range

Negative (blaGES gene not detected). Results reported as Detected or Not Detected for the presence of the blaGES carbapenemase gene.N/A

Specimen: serum

No special patient preparation required. Specimen should be collected prior to initiation of antimicrobial therapy when clinically feasible. Standard aseptic technique must be observed during specimen collection to prevent contamination.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

How often do I need this test?
Your doctor will determine frequency based on your health status. Regular monitoring may be needed if you have chronic kidney disease, diabetes, or high blood pressure.
Can diet affect creatinine levels?
Dietary protein intake can influence creatinine levels, but the test itself measures waste from muscle breakdown. Avoid extreme protein restriction unless advised by a dietitian.
What if my results are out of range?
If results are abnormal, your provider will discuss next steps, which may include more tests, lifestyle changes, or treatment adjustments tailored to your condition.
  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