Polymorphs in Blood: Normal Range, Test, High & Low Levels Explained
Time to read 5 min
Time to read 5 min
Table of contents
Polymorphs in blood are an important part of your body’s defence system. They are a type of white blood cell (WBC) that helps fight bacterial infections, remove damaged tissue, and support your immune response. When you do a complete blood count (CBC) test, the differential count section usually shows the percentage of polymorphs or neutrophils in your blood.
Understanding what polymorphs do, their normal range, and the causes behind high or low levels can help you and your doctor interpret your blood test results correctly.
Polymorphs, also known as polymorphonuclear leukocytes (PMNs), are a group of white blood cells with multi-lobed nuclei. They mainly include neutrophils, eosinophils, and basophils—all produced in the bone marrow.
These blood cells play a crucial role in the innate immune system, which is your body’s first line of defence against infections. When pathogens enter your body, polymorphs rush to the site of infection and destroy harmful microbes through an inflammatory response.
Neutrophils form the majority of polymorphs. They help fight bacterial infections and are among the first cells to reach the infection site. An increased percentage of neutrophils (or high neutrophil percentage) often indicates an acute infection.
These are responsible for responding to parasitic infection and allergic reactions, as well as other viral infections . A rise in eosinophils may point to asthma, allergy, or certain inflammatory diseases.
The least common type, basophils, release histamine during allergic responses and inflammation. They are associated with chronic forms of infection or inflammation.
Though not polymorphs, monocytes and lymphocytes (T cells and B cells) also appear in the differential count. Together, they maintain the proper proportion of white cells necessary for a balanced immune system.
Knowing the normal range of polymorphs in blood helps doctors assess your immune response and overall blood count. The absolute neutrophil count (ANC) and differential count are especially useful.
Population Group |
Normal Range (%) |
Normal Range (Absolute Count) |
|---|---|---|
General Adult |
40–75% of total WBCs |
1,500–8,000 cells/µL |
Adult Male |
Similar to general adult range |
Similar values |
Adult Female |
Similar to general adult range |
Similar values |
Children |
Varies by age |
Depends on age-specific reference |
Pregnancy |
60–80% (slightly higher) |
Elevated ANC values |
When the percentage of polymorphs or neutrophils is higher than normal, it is called neutrophilia. This condition may occur due to:
A rise in polymorphs commonly occurs with bacterial infections such as streptococcus bacteria or group A streptococcus bacteria that cause sore throat or tonsillitis, as well as blood cancer.
Conditions such as rheumatoid arthritis or inflammatory bowel disease (IBD) can lead to an inflammatory response that increases polymorph levels.
Certain bone marrow diseases, such as leukaemia or myeloproliferative diseases, result in excessive blood cells produced in the bone marrow.
Acute stress, trauma, cigarette smoking, or steroid use may temporarily elevate neutrophil percentage.
Parasitic infection or viral infections
Radiation therapy
Certain medications that stimulate adrenal glands
Chronic inflammation due to liver swelling or thyroid disease
A decreased percentage of polymorphs, or neutropenia, indicates a reduced ability to fight infection. A decreased percentage of polymorphs, or neutropenia, indicates a reduced ability to fight infection. Possible causes include abnormal or immature cells.
Bone marrow invasion from blood cancer or bone marrow cancer
Viral infections such as influenza or hepatitis
Radiation therapy or chemotherapy
Certain medications that suppress the immune system
Multiple myeloma or other blood diseases
If immature white blood cells or abnormal or immature cells are seen in a peripheral blood smear, it may indicate bone marrow dysfunction and needs medical evaluation.
A polymorph count is part of a complete blood count (CBC) test. The laboratory methods are simple:
Draw blood from a vein in your arm.
The blood drawn is analysed under a microscope.
A blood differential test measures the number of each cell type—including polymorphs.
The procedure involves only a prick, and most people feel moderate pain or slight discomfort. Occasionally, you may notice throbbing or slight bruising, or feel lightheaded if multiple punctures are required. There is a slight risk of excessive bleeding or fainting, especially if arteries vary or veins are small.
High or low polymorphs often do not cause symptoms on their own but may occur with:
Swollen lymph glands
Fever, sore throat, or fatigue
Liver swelling or body pain
Uric acid buildup due to rapid blood cells produced
Seek medical help if you experience persistent fever, fatigue, or infections that do not heal. In severe cases, abnormal polymorph levels may indicate a medical emergency such as leukaemia or severe bacterial infection.
Polymorphs are vital for protecting the human body from pathogens. They attack microbes, help repair tissues, and prevent the spread of infection.
The innate immune system, which includes mast cells and neutrophils lymphocytes, responds rapidly to infection. If the proper proportion of white cells is not maintained, the body becomes more vulnerable to diseases.
Doctors use both absolute count and percentage count, including the absolute neutrophil count, to assess your immune response. The medical history of a patient—including recent infection, medication, or stress—is important for correct interpretation.
A result outside the normal range does not always mean disease. For example:
Increased percentage may appear after acute infection or steroid use.
Decreased percentage could follow a viral illness or medication course.
Consult your healthcare provider for correlation with symptoms and further tests like Henry’s Clinical Diagnosis or bone marrow examination if needed.
Polymorphs in blood are essential defenders of the immune system. Abnormal levels—whether high or low—can signal infection, inflammation, or serious blood diseases. A complete blood count (CBC) with differential count helps doctors evaluate your immune response and overall health.
If your test shows abnormal polymorph levels, don’t panic—consult your healthcare provider for further evaluation and treatment.
The test helps evaluate the number and type of white blood cells (WBCs), especially neutrophils, to detect infections, inflammation, or bone marrow diseases.
High polymorphs usually indicate an active bacterial infection or inflammation. Persistently high levels may signal bone marrow cancer or chronic inflammatory diseases, which require medical attention.
Levels usually normalise within a few days after the acute infection or inflammation resolves. However, chronic illnesses or bone marrow disorders may take longer.
Yes, acute stress or even intense physical exercise can cause a temporary rise in neutrophil percentage due to hormonal changes in the adrenal glands.
Low polymorphs could mean a viral infection or bone marrow suppression. It’s important to discuss results with your doctor, especially if you have frequent infections or prolonged fatigue.
* Medical Disclaimer - The following information is for educational purposes only. No information provided on this website, including text, graphic, and images, are intended as substitutes for professional medical advice. Please consult with your doctor about specific medical advice pertaining to your condition(s).
