Neutrophils – Your Body's First Line of Immune Defense
Neutrophils are a type of white blood cell (granulocyte) that accounts for 40–75% of all leukocytes. They are produced in the bone marrow and are the first cells to arrive at the site of infection, where they engulf and destroy bacteria and fungi. A neutrophil count is a key part of the differential white blood cell count.
Why Test Neutrophils?
Testing neutrophils helps evaluate immune defense, detect infections, investigate inflammation, and monitor bone marrow function. It is particularly important during chemotherapy or immunosuppressive treatment, when neutropenia increases the risk of serious infections.
What Do High Neutrophils Levels Mean?
Elevated neutrophils (neutrophilia) may indicate bacterial infection, acute inflammation, physical or emotional stress, smoking, cortisone therapy, or blood disorders like leukemia.
What Do Low Neutrophils Levels Mean?
Low neutrophils (neutropenia) suggest a weakened immune system. Causes may include viral infections, bone marrow disorders, autoimmune diseases, B12 or folate deficiency, or chemotherapy.
Symptoms to Watch For
- Recurrent infections
- Fever without a clear cause
- Fatigue and weakness
- Mouth ulcers
- Slow wound healing
- Bruising easily
Who Should Get Tested?
- People with recurrent or severe infections
- Patients undergoing cancer treatment
- Those with unexplained fever or fatigue
- Anyone with suspected blood or bone marrow disease
- Individuals monitoring immunosuppressive therapy
How to Prepare for Your Test
No special preparation is needed. Bring valid ID to your appointment.
Frequently Asked Questions
What is a normal neutrophil count?
Can an infection cause both high and low neutrophils?
Is neutropenia dangerous?
Reviewed by
Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
Learn more about our team →Medical Disclaimer
The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.