Joint fluid leukocyte count (with differential)
This test measures the number of white blood cells in fluid collected from a joint, often to help diagnose conditions like arthritis or infections.
["White blood cells in joint fluid can signal inflammation, infection, or other joint issues."]
Key facts at a glance
- LOINC
- 26227-9
- Short code
- MR LE joint-Bl
- Synonyms
- MR LE joint-Bl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- mr
- 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 Is Done
Doctors may order this test if you have symptoms like joint pain, swelling, or redness that could indicate conditions such as arthritis, gout, or infections like septic arthritis. It helps determine whether fluid buildup is due to inflammation, infection, or other causes.
What to Expect Before the Test
You’ll likely have a small needle inserted into your joint (e.g., knee, shoulder) to collect fluid. The procedure is quick and usually painless, though you may feel some discomfort afterward. Wear loose clothing and bring any medications you’re taking.
What the Test Results Mean
Higher-than-normal white blood cell counts may suggest inflammation (e.g., rheumatoid arthritis) or infection. Lower counts might indicate conditions like gout or other crystalline deposits. Differential counts (breaking down WBC types) can further clarify the cause.
Common Conditions Linked to This Test
Results often guide treatment decisions, such as whether you need antibiotics for infection, anti-inflammatory medications for arthritis, or further imaging to diagnose joint damage.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: Elevated leukocyte counts in joint fluid are often diagnostic for inflammatory or infectious processes, while specific patterns (e.g., high neutrophils vs. lymphocytes) can narrow down suspected conditions like septic arthritis, gout, or pseudogout. Low counts may suggest non-inflammatory causes like crystal deposition.
Short name
Joint fluid WBC count
Frequently asked questions
What causes joint fluid to have unusual white blood cell counts?
How soon will I know my results?
Can I take anything to prepare for this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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