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Cytochemical examination of peripheral blood cells (manual differential count)

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

This test helps identify and count different types of white blood cells in your blood, which can help diagnose infections, blood disorders, or other health conditions.

Quick summary

["This test helps doctors understand your immune system and blood health."]

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

Key facts at a glance

LOINC
55601-9
Short code
Cyto Pcar
Synonyms
Cyto Pcar
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
cyto-stain
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

What This Test Measures

A blood sample is examined under a microscope to count and classify five main types of white blood cells: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. This process is often part of a complete blood count (CBC) but can be performed separately for detailed analysis.

Why It’s Done

Doctors may order this test to check for infections (like bacterial or viral), monitor immune system function, detect blood disorders (such as leukemia or anemia), or evaluate conditions like allergies or autoimmune diseases.

Sample Collection and Preparation

A small blood sample is drawn from a vein, typically in your arm. The sample is then processed and stained to highlight different cell types before being viewed under a microscope.

What to Expect Before the Test

There may be mild discomfort during the blood draw, but no special preparation is needed. If you’re on blood-thinning medication, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal counts of white blood cells can signal infections, inflammation, or immune system issues. For example, high neutrophil counts might indicate infection, while low lymphocyte counts could suggest immune deficiency or certain cancers. This test helps guide treatment decisions and ongoing monitoring.

Short name

Blood Cell Type Analysis

Frequently asked questions

How long does it take to get results?
Results are usually available within 1 to 2 business days, depending on lab processing times.
What does each white blood cell type represent?
Neutrophils fight bacterial infections; lymphocytes manage immune responses; monocytes help fight chronic infections; eosinophils are linked to allergies or parasitic infections; basophils release chemicals involved in allergic reactions.
Can I eat or drink before this test?
No special diet is required, but avoid heavy meals or alcohol before the blood draw to ensure accurate results.
  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