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Leukocyte Count (Acute Phase Response Indicator) – Whole Blood

Published: August 9, 2026Updated: August 16, 2026

This test measures the total number of white blood cells in your blood. White blood cells help your body fight infections and respond to inflammation.

Quick summary

["Your white blood cell count can signal infection, inflammation, or other health concerns."]

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

Key facts at a glance

LOINC
72103-5
Short code
Acute+chron leuk Pnl Bld/T
Synonyms
Acute+chron leuk Pnl Bld/T
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
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 Might Be Ordered

Your healthcare provider may order this test to check for signs of infection, inflammation, or other conditions affecting your immune system. It can also be used during monitoring for chronic illnesses like cancer, autoimmune diseases, or after treatments that affect the immune system.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm or vein to draw blood. It usually takes a few minutes, and you may feel a brief pinch or discomfort.

What the Test Results Mean

Results are typically reported as the total number of white blood cells per microliter (cells/µL) of blood. High or low counts can indicate different health issues, so your provider will interpret the results in the context of your overall health and symptoms.

Common Conditions Affecting Results

High white blood cell counts may be linked to infections, inflammation, stress, or certain medications. Low counts can suggest immune deficiencies, infections, or blood disorders. Chronic conditions like leukemia or lymphoma may also affect this count.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Leukocyte Count (Acute Phase)

Frequently asked questions

What does a high white blood cell count usually mean?
A high white blood cell count often signals an active infection, such as a bacterial or viral infection, or an inflammatory process. It can also occur due to stress, certain medications, or conditions like leukemia. Your provider will review your symptoms and other test results to determine the cause.
What does a low white blood cell count usually mean?
A low white blood cell count may indicate an immune system issue, such as HIV/AIDS, certain cancers, or autoimmune diseases. It can also result from chemotherapy, radiation therapy, or blood disorders. Your provider will assess your health history and other tests to identify the reason.
How often should I get this test?
The frequency of this test depends on your medical condition and treatment plan. If you have a chronic illness or are undergoing treatment, your provider may recommend regular monitoring. If you’re healthy, this test is usually not routinely ordered unless you have symptoms or risk factors.
  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