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Serum or Plasma Creatinine Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 15, 2026

This test measures the amount of creatinine, a waste product from muscle breakdown, in your blood. It helps assess how well your kidneys are filtering blood.

Quick summary

["A creatinine test checks kidney function by measuring waste in your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
109199-0
Short code
BHMIgM
Synonyms
B hermsii IgM Msmt Ser
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube
Units
N/A
Ref low
20
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunofluorescence Assay (IFA) or Enzyme Immunoassay (EIA)
CPT
86618
SNOMED
417460008
Specimen volume
1-2 mL serum
Stability
Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
48–120 hours
Order
routine

Why This Test Matters

Creatinine is a byproduct of muscle metabolism that your kidneys normally filter out of your blood. High levels can signal kidney problems, while low levels might indicate dehydration or other conditions. This test is often used alongside other kidney function tests to monitor overall kidney health.

What to Expect Before the Test

No special preparation is needed, but you may be asked to avoid certain medications or foods that could affect results (like contrast dyes for imaging). Drink plenty of water the day before if your doctor recommends it, as hydration can help prepare your kidneys.

During the Test

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The blood sample is sent to a lab for analysis.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or micromoles per liter (µmol/L). While reference ranges vary by lab, higher than expected levels may indicate reduced kidney function, while very low levels could suggest dehydration or other issues. Your doctor will interpret results in the context of your overall health.

Reference range

Negative: <1:20 titer; Equivocal: 1:20-1:40; Positive: ≥1:80N/A

Specimen: serum

No special preparation required. Patient should inform provider of recent antibiotic use and travel/exposure history to soft tick areas.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Creatinine Level

Frequently asked questions

What does a high creatinine level mean?
High creatinine levels often signal impaired kidney function, as your kidneys struggle to filter waste properly. This can be due to chronic kidney disease, kidney stones, or other conditions affecting blood flow to the kidneys. Your doctor may recommend further testing or adjustments to your treatment plan if levels are elevated.
What does a low creatinine level mean?
Low creatinine levels may indicate dehydration, muscle atrophy (loss of muscle mass), or certain metabolic conditions. In some cases, it could also suggest an overactive thyroid or other hormonal imbalances. Your doctor will consider other factors, such as your diet, hydration status, and medical history, to understand the cause.
Can diet affect creatinine levels?
Yes, diet can influence creatinine levels. High-protein foods (like red meat or processed meats) can temporarily raise creatinine levels because they increase muscle breakdown. Conversely, dehydration can also elevate creatinine. Your doctor may advise you to avoid certain foods or drinks before testing if they suspect dietary influences.
  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 15, 2026. · Read our editorial policy