Elevated Leukocytes: Causes of Leukocytosis and What It Means

You opened your test results and saw a number above normal. The first thought is usually about cancer. Let's figure out what this indicator shows and when it requires attention.

What are leukocytes and what is their normal range

Leukocytes are white blood cells. They are part of the immune system, mature in the bone marrow, and work in the blood and lymphoid tissue.

In case of injury or illness, leukocytes go where help is needed. There they fight bacteria, viruses, and other foreign agents.

There are five main types: neutrophils, lymphocytes, monocytes, eosinophils, basophils. A complete blood count measures their total, while the leukocyte differential counts each type separately.

For pregnant women, women in labor, and children, separate norms apply. Physical exertion and food intake can temporarily change the indicator.

What it means when blood leukocytes are elevated

An increase in the number of leukocytes is called leukocytosis. This is how the body reacts to illness: it makes more protective cells.

The test itself does not make a diagnosis. It shows that there are more cells than normal and does not explain why.

Sometimes leukocytosis is detected only during a routine complete blood count. Sometimes there is also malaise, fatigue, elevated temperature, sweating, dizziness, loss of appetite, joint and muscle pain, sleep disturbance.

With an infection, there may be fever, chills, body aches, headache, a persistent cough, a wound with pus that does not heal.

Common causes of leukocytosis

Causes are divided into physiological and pathological. In the first case, the number of cells increases temporarily and returns to normal on its own.

• Food: after eating, the number of leukocytes increases, but not above 10–12×10⁹/L.
• Physical work, sports, hot and cold baths, banya, sauna, hot air.
• Pregnancy and childbirth, the second half of pregnancy, the premenstrual period.
• Smoking and stress, strong emotional experiences.
• Some foods in the diet.

Pathological leukocytosis occurs with infections: pneumonia, sepsis, meningitis, pyelonephritis, infectious mononucleosis. It is also caused by inflammations—peritonitis, phlegmon, rheumatoid arthritis, systemic lupus erythematosus.

Other causes: myocardial or pulmonary infarction, extensive burns, major blood loss, uremia, diabetic coma, removal of the spleen. After splenectomy, leukocytes remain at 15–20×10⁹/L, neutrophils up to 90%.

Is leukocytosis cancer? Leukocytes in oncology

No, not necessarily. Leukocytes increase with infections, inflammation, allergies, burns, stress, smoking, pregnancy, and cancer is only one of the possible causes. The test itself does not confirm a diagnosis.

In oncology, high leukocytes occur in leukemias and Hodgkin's disease. In leukemias, an increase is seen only in the leukemic form (above 50–80×10⁹/L) and subleukemic form (50–80×10⁹/L).

In the leukopenic and aleukemic forms, the numbers will be low. Bone marrow metastases also disrupt hematopoiesis and cause leukopenia.

Some infections proceed without an increase in leukocytes: typhoid fever, malaria, brucellosis, measles, rubella, influenza, viral hepatitis in the acute phase.

How a doctor determines the cause of high leukocytes

One indicator alone decides nothing. The doctor looks at symptoms, medical history, and other tests.

Usually a complete blood count, leukocyte differential, blood smear, and sometimes a bone marrow examination are prescribed. The differential clarifies the picture: neutrophils more often respond to bacteria, lymphocytes to viruses. Their increase is called neutrophilia and lymphocytosis.

There is no separate treatment "for leukocytes." Therapy is aimed at the cause that raised them.

When to see a doctor

Discuss the elevated indicator with a doctor: they will assess symptoms, medical history, and other tests. Reasons not to postpone a visit: fever, chills, body aches, headache, persistent cough, a wound with pus.

Self-treatment does not work here. Only a doctor determines why the cells are increasing and distinguishes a temporary shift from a disease.

Leukocytosis alone is not a reason to call an ambulance. 103 or 112—for a life-threatening condition, for example, signs of stroke or heart attack.

This material is for reference and does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer