High white blood cell count: causes and what to do
White blood cells most often rise because of an infection or inflammation, but also after stress or hard exercise, during pregnancy and in smokers. For adults, doctors go by a range of roughly 4–10 ×10⁹/L, with an upper limit of 11 in some labs, so check the range on your report. For a small rise without symptoms, the doctor often suggests a repeat test, and if your count stays high with no clear cause, it's worth showing your results to a hematologist.
What white blood cells and the differential are
White blood cells, or leukocytes, protect the body from infection. There are five types, and each has its own job:
- neutrophils are the first to arrive wherever there are bacteria or fungi, and there are more of them in the blood than any other type;
- lymphocytes recognize viruses and produce antibodies;
- monocytes engulf microbes and the remains of damaged cells;
- eosinophils take part in allergic reactions and defense against parasites;
- basophils are the rarest and are also involved in allergies.
The differential shows what share of all white blood cells each type makes up, and often the absolute number of these cells as well. Doctors look mainly at the absolute numbers, because the percentage of lymphocytes can go up simply because there are fewer neutrophils.
On your report, the total white blood cell count is labeled WBC. When it’s above the upper limit of normal, this is called leukocytosis.
Why is my white blood cell count high?
Most often, leukocytosis means your body is fighting an infection or inflammation. White blood cells go up with:
- bacterial infections, such as tonsillitis, pneumonia or a kidney infection;
- viral infections, although with these the total count more often stays normal;
- inflammatory diseases without infection, injuries, burns and surgery;
- severe stress, pain or a hard workout the day before the test;
- pregnancy and the first days after childbirth;
- smoking: smokers often have a slightly higher count all the time;
- certain medicines, including steroid anti-inflammatory drugs;
- removal of the spleen.
Which cells have gone up also gives a clue. Neutrophils increase with bacterial infection, inflammation and after stress. Lymphocytes go up with viral infections and whooping cough, and if an older person’s lymphocytes stay high without an infection, it’s worth showing the results to a hematologist. Monocytes rise with lingering infections and during recovery. Eosinophils go up with allergies, asthma, eczema, parasitic worm infections and drug reactions. Basophils rarely rise, and the doctor will investigate a persistent increase.
When to see a hematologist about a high white blood cell count
A small rise during or right after a cold usually settles once you recover. It’s worth showing your results to a hematologist at Viva Clinic if:
- your count stays high on repeat tests over several weeks and no cause has been found;
- your count is several times higher than the upper limit of normal;
- the differential shows immature cells, such as blasts or myelocytes;
- your hemoglobin or platelets are abnormal at the same time;
- your lymph nodes are swollen, you sweat at night, you’re losing weight for no reason, or you have a fever that nothing explains.
If blasts are found on your blood test, see a doctor the same day.
The Viva Clinic hematologist will help with the tests you need and, if you need treatment at a specialist hematology center, for example for leukemia or lymphoma, give you a referral. The hematologist sees patients at 27a Sobornosti St or 3 Danyla Halytskoho St (the exact address is confirmed when you book). The consultation is paid, you don’t need a referral, and you can book by phone or on Viber.
What does a low white blood cell count mean?
When you have fewer than 4 ×10⁹/L white blood cells, or fewer than the lower limit on your report, this is called leukopenia. It often happens after viral infections, including flu, and the count recovers once you’re well. White blood cells can also be lowered by certain medicines, autoimmune diseases, a lack of vitamin B12 or folate and, less often, bone marrow disorders. Show a result like this to a doctor. If your count is low and you develop a fever, a sore throat or mouth ulcers, see a doctor the same day.
How to get tested, and why not to take antibiotics based on a blood test
White blood cells and the differential are measured as part of a complete blood count with differential. You can have it at Viva Clinic’s Diagnost-Lab laboratory at 32 Sobornosti St, 4th floor. If you have signed a declaration with a Viva Clinic family doctor (in Ukraine, this is how you register with a primary care doctor), the test is free when that doctor orders it. Avoid intense exercise the day before, because physical exertion temporarily raises white blood cells. For other tips on preparing, see the article on the complete blood count.
A high white blood cell count doesn’t mean you need an antibiotic. Antibiotics don’t work against viruses, while white blood cells also rise with viral infections, inflammation without infection or after stress. An antibiotic taken “just in case” won’t help, but it can cause side effects and make bacteria resistant to medicines. In Ukraine, antibiotics are sold only with a prescription, which since 1 August 2022 can also be electronic, so they are prescribed by a doctor after an examination.
Call an ambulance (103) if a high fever with chills comes with confusion, fast breathing, sudden severe weakness or a rash that doesn’t fade when you press on it.
Questions and answers
Can white blood cells be high without a fever?
Yes. White blood cells can rise without a fever after a recent infection, with chronic inflammation, in smokers, during pregnancy, or after stress or a workout the day before the test. If the rise is small and you feel fine, your doctor will usually suggest repeating the test in a few weeks.
How quickly does the white blood cell count return to normal after an illness?
Usually within a few weeks of recovery. If your count is still high a month or two later and there's no obvious reason, show your results to an internist, family doctor or hematologist. It's best to have a routine follow-up test once you're well.
What is a normal white blood cell count for a child?
It's higher than in adults and depends on age: babies have the most white blood cells, and the number gradually falls as children grow. That's why a child's results aren't compared with adult ranges. A pediatrician assesses them, taking into account the child's age, how they feel and any recent illnesses.
Does a high white blood cell count need treatment?
The count itself isn't treated. Once the infection or inflammation clears up, white blood cells return to their usual level on their own. There's no need to look for ways to 'lower white blood cells': the doctor finds out why they went up and treats that cause.
