They are the primary white blood cells that respond to a bacterial infection, so the most common cause of neutrophilia is a bacterial infection.
Neutrophilia is an increase in circulating neutrophils above what is expected in a healthy individual of the same age, sex, race, and physiological status.
This represents an increase in neutrophil count above 7.5 x 109 / l and is one of the most frequently observed changes in BCF.
Causes of Neutrophilia Infections
- Acute and chronic bacterial infection, especially pyogenic, local or generalized bacteria, including miliary tuberculosis.
- Some viral infections (e.g., chickenpox, herpes simplex).
- Some fungal infections.
- Some parasitic infections (e.g., hepatic amoebiasis, Pneumocystis carinii).
It is usually due to a redistribution of white blood cells or increased bone marrow production.
Neutrophilia can occur as a normal physiological process. Healthy newborns have a higher neutrophil count, and for babies less than one-month-old the normal range is as high as 26 × 109 / L.
Women of childbearing age have higher neutrophil counts than men, and the count varies during the menstrual cycle.
Pregnancy causes a marked increase in the neutrophil count, which increases even more during and after delivery. Vigorous exercise can double the neutrophil count by altering the distribution of white blood cells within the circulation.
Neutrophilia in pathological conditions is generally due to increased bone marrow production.
Reactive neutrophilia, where the cause is extrinsic factors rather than a primary hemopoietic disorder, is expected, with infection being the most common cause.
Symptoms of high neutrophils
Some symptoms can be:
- Morning stiffness.
- Low lymphocyte count.
- Heberden’s nodules.
- Unexplained fevers
- High serum iron.
- High basophil count.
- Long-term neck pain.
- Dry eyes.
Diagnosis of high neutrophils
Most often, neutrophilia will be a reactive phenomenon, usually a bacterial infection in which fever may also occur due to the release of leukocyte pyrogens.
Neutrophilia usually does not cause symptoms, and no direct adverse effects are known until the count is exceptionally high, as seen in myeloproliferative disorders, such as chronic myeloid leukemia.
About 15 percent of these patients will have a white blood cell count greater than 300 × 109 / L when signs and symptoms of leukostasis develop from impaired microcirculation in the lungs, brain, eyes, ears, or penis.
Patients may have tachypnea, dyspnea, cyanosis, dizziness, slurred speech, delirium, stupor, visual blurring, diplopia, retinal vein distention, retinal hemorrhages, papilledema, tinnitus, hearing problems, or priapism.
A careful review of the blood film can explain the underlying etiology.
Inflammation of any severe causes to cause intensely accelerated neutrophil production will produce cytoplasmic toxic granulation changes and vacuolation. However, the presence of neutrophil vacuolation is more specific for infection, most commonly septicemia.
Dohle bodies, basophilic inclusions in the cytoplasm, may also be present.
Other features of reactive neutrophilia include a “left shift” in the peripheral blood differential white cell count or an increase in the number of band forms with the occasional presence of cells such as metamyelocytes and myelocytes.
Occasionally this change is more pronounced with excessive leukocytosis and the appearance of immature myeloblasts when it is called a leukemic reaction and resembles certain forms of myeloid leukemia.
Associated disorders include severe or chronic infections, severe hemolysis, or metastatic cancer. Leukemic reactions are more marked in children.
Rouleaux may be present, and the platelet count may rise during an acute phase response. Normochromic normocytic anemia can develop, and if the inflammatory process is chronic, the red blood cells can become hypochromic and microcytic.
If neutrophilia is associated with myelocytes, promyelocytes, and increased basophils in the setting of splenomegaly, a primary hematologic cause, such as a myeloproliferative disorder, should be considered.
Treatment of high neutrophils
Specific treatment, if indicated, is generally directed at the underlying cause of the neutrophilia. Hyperleukocytosis requires urgent treatment with leukapheresis, hydration, and cytoreductive therapy with hydroxyurea.
Referral to a hematologist should be considered when neutrophilia occurs in association with splenomegaly and other abnormalities of the BCF to exclude an underlying hematologic disorder. After a blood film review, a bone marrow sample will usually be taken to establish the diagnosis.
In patients with a primary hematologic diagnosis, such as a myeloproliferative disorder, treatment may include cytotoxic agents, including hydroxyurea, to control blood counts.
Such therapy requires close specialist supervision with regular blood counts due to the risk of severe, life-threatening bone marrow suppression.
In patients with chronic myeloid leukemia, the mainstay of treatment is imatinib, a tyrosine kinase inhibitor. Again, this requires specialized supervision.