Blood count and blood group · Blood

Leukocytes (white blood cells)

The total number of white blood cells, the immune cells; rises with infections and inflammation, falls with some medicines.

At a glance

Measured in blood
In 15 test panels
No special preparation

Explanation

Leukocytes (white blood cells): what is measured?

The analysis counts the total number of white blood cells (leukocytes) per liter of blood. White blood cells are made in the bone marrow and protect the body against bacteria, viruses and other invaders. There are five types (neutrophils, lymphocytes, monocytes, eosinophils and basophils), each with its own task; the total number shows whether the immune system is in action or, on the contrary, weakened, while the distribution over the types (the differential) says more about the cause.

What can it detect?

Infections and inflammation (usually a raised count)
A weakened immune system due to medicines, chemotherapy, radiotherapy, a viral infection or an autoimmune disease (low count)
Rarely: a blood disease such as leukemia, in which white blood cells are produced uncontrollably (strongly raised or, on the contrary, low count with other abnormalities)

Result

What does the result mean?

Leukocytes (white blood cells) too high

A raised number of white blood cells (leukocytosis) is usually a normal reaction to an infection or inflammation, for example a cold, bladder infection, pneumonia or an inflamed joint. Stress, heavy exercise, smoking, pregnancy, surgery or injury and medicines such as prednisone also temporarily raise the count. The count usually falls again on its own once the cause is over. Rarely: a blood disease such as leukemia, especially with a strongly raised count together with a low hemoglobin or abnormal platelets. The GP then has the blood examined under the microscope and refers you to a hematologist if needed.

Leukocytes (white blood cells) too low

A low number of white blood cells (leukopenia) is common during or shortly after a viral infection, such as flu or COVID, and then recovers within a few weeks. Other causes are medicines (including chemotherapy, methotrexate, some antibiotics, anti-epileptic drugs and thyroid-suppressing drugs), an autoimmune disease, a vitamin B12 or folic acid deficiency, excessive alcohol use or an enlarged spleen. People with an African or Middle Eastern background often naturally have a lower number of neutrophils without anything being wrong. With a strongly low count, the defense against bacteria is reduced; fever then needs prompt assessment by a doctor. Rarely, a persistently low count, together with anemia or too few platelets, points to a bone marrow disorder; the GP then looks into this further.

After an abnormal result

With a slightly abnormal count without symptoms, the GP usually repeats the measurement after a few weeks, once any infection is over. With a persistent or strongly abnormal count, the GP has a differential done and the blood examined under the microscope, and refers you to an internist (specialist in internal medicine) or hematologist if there are signs of a bone marrow disorder.

Reliability

How reliable is the test?

Counting white blood cells is accurate, but the number fluctuates strongly from day to day and even within a day. An abnormal count can therefore rarely be interpreted on its own: it gains meaning in combination with symptoms, the differential (which type is abnormal), the hemoglobin and the platelets. According to the Dutch GP guideline (NHG) on anemia, an abnormal number of white blood cells together with anemia is a reason to consider a bone marrow disorder and to consult a specialist. In healthy people without symptoms, a slightly abnormal count is almost always temporary.

What can affect the result?

An infection or inflammation in the weeks before the blood draw, even an ordinary cold, temporarily changes the count.
Heavy exercise, stress, smoking, pregnancy and medicines such as prednisone raise the count; chemotherapy, methotrexate and some antibiotics or anti-epileptic drugs lower it.
The count has a daily rhythm and is higher in the afternoon than in the morning.
In blood that takes a long time to reach the laboratory, white blood cells are harder to count and distinguish.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that point to an infection or inflammation, with persistent fever or tiredness without a clear cause, with repeated infections, for monitoring during medicines that suppress the bone marrow or the immune system (such as methotrexate or chemotherapy) and as part of a blood count in anemia. In healthy adults without symptoms, the chance of a meaningful abnormality is small; a slightly abnormal count is then usually temporary.

How common is it?

A temporarily raised or low number of white blood cells is very common, usually due to an infection, inflammation or medicines. A persistently strongly abnormal count due to a bone marrow disease is rare, and very rare in young adults.

Drawbacks and risks

A slightly abnormal number of white blood cells is common in healthy people and almost always temporary; without a repeat measurement, the result can cause unnecessary worry about a blood disease.
A normal count does not rule out an infection; many viral infections give a normal or slightly low count.

Get tested

Leukocytes (white blood cells): test panels

Leukocytes (white blood cells) is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Vegan Test
Panel for vegetarian or vegan diet; B12 D iron and more.
€ 116,00
Blood draw
General Health Checkup
With this General Health Check-up, you gain detailed insight into your overall health and well-being.
€ 125,00
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Blood Count
Blood Count; complete analysis of blood cells for detection of anemia and infections.
€ 19,00
Blood draw
Complete Blood Count (CBC)
Complete Blood Count Extended; standard blood count plus detailed white blood cell analysis.
€ 27,00
Blood draw
PhenoAge
PhenoAge Biological Age Test; determine your biological age with 9 standard blood values.
€ 85,00
Blood draw
InsideTracker
InsideTracker Blood Analysis: analyze 48 biomarkers for complete health optimization and personalized recommendations.
€ 335,00
Blood draw
Endurance Sports
Complete blood count, iron status (ferritin, transferrin), kidney function, liver function, testosterone, and hs-CRP. For athletes and endurance sport participants.
€ 203,00
Blood draw
Comprehensive Fatigue Test
Vitamin D, B12, TSH, fT4, glucose, MCV, ferritin, ESR and complete blood count. For persistent fatigue with inflammation check.
€ 152,00
Blood draw
Extended Cholesterol Test
Comprehensive cholesterol test with vitamin D, B12, and blood count. Combines heart health with a fatigue check in one package.
€ 98,00

How reliable is the test?

Leukocytes (white blood cells)