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Neutrophil count with differential (serum/plasma-based neutrophil fraction estimation)

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

This test evaluates the proportion of neutrophils in your blood, which helps assess immune response and inflammation. Neutrophils are a key white blood cell type that fight infections.

Quick summary

["Neutrophils help your body detect and respond to infections, but elevated or low levels may signal health concerns."]

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

Key facts at a glance

LOINC
73042-4
Short code
CTRX-NAB
Synonyms
cefTRIAXone (neut) IgG SerPl Ql FC
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube for serum; EDTA tube acceptable for plasma
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
86022
SNOMED
122729007
Specimen volume
5-10 mL of whole blood yielding 2-3 mL of serum or plasma
Stability
Serum/plasma stable for 48 hours at 2-8°C; for prolonged storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
48–168 hours
Order
routine

What Neutrophils Do in Your Body

Neutrophils are a type of white blood cell that play a critical role in fighting bacterial infections. When you have an infection, your body produces more neutrophils to help clear the bacteria. This test measures the percentage of neutrophils in your blood, which can give clues about your immune system’s activity.

When This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like frequent infections, unexplained fevers, or signs of inflammation. It can also be part of routine blood work to monitor conditions such as autoimmune diseases or certain cancers.

How the Test Works

This test involves drawing a small amount of blood from your arm. The blood is then analyzed to estimate the fraction of neutrophils. The method may use a specialized blood test or a blood smear to count and identify these cells under a microscope.

What to Expect Before the Test

There are usually no special preparations needed for this test. You may have some mild discomfort from the needle, but it typically goes away quickly. If you’re on blood-thinning medication, let your doctor know before the test.

Reference range

Negative: No detectable cefTRIAXone-induced neutrophil IgG antibodies. Positive: Presence of drug-dependent neutrophil-reactive IgG antibodies detected, suggesting immune-mediated hypersensitivity to cefTRIAXone.N/A

Specimen: serum

No special patient preparation is required. Specimen should be collected prior to initiation of immunosuppressive therapy when possible. Recent transfusion history should be noted as it may affect neutrophil antibody detection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High neutrophil counts (neutrophilia) may indicate acute infections, stress, or certain inflammatory conditions. Low neutrophil counts (neutropenia) can make you more susceptible to infections and may signal underlying issues like autoimmune disorders or bone marrow problems. Your doctor will use these results along with other factors to guide treatment.

Short name

Neutrophil Profile

Frequently asked questions

Why might my neutrophil count be checked regularly?
Regular checks may be needed if you have a chronic condition like leukemia, HIV, or certain autoimmune diseases. Doctors also monitor neutrophil levels in patients receiving chemotherapy or other treatments that suppress the immune system.
What does a high neutrophil count mean?
A high neutrophil count often signals an active infection, inflammation, or stress response. It can also occur with certain medications or conditions like rheumatoid arthritis. Your doctor will discuss the results with you and may recommend further testing if needed.
Can diet or lifestyle affect neutrophil counts?
Diet and lifestyle factors like poor nutrition, chronic stress, or smoking can influence white blood cell counts, including neutrophils. Avoiding excessive alcohol, maintaining a balanced diet, and managing stress may support your immune system, but this test specifically measures the neutrophil fraction in your blood.
  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