Psoriasis is an immune-related condition that causes skin inflammation, and inflammation can sometimes be linked with a higher white blood cell count. However, a high count is not a usual way to diagnose psoriasis, and it should not automatically be blamed on the skin condition. Infection, medicines, stress, smoking, and other illnesses may also raise white blood cells, so the result needs to be reviewed in context.
Can psoriasis cause a high white blood cell count?
Psoriasis involves an overactive immune response that speeds up skin cell production and causes inflammation. This inflammation may contribute to changes in certain blood markers in some people, but a raised white blood cell count is not a reliable measure of psoriasis activity in every case.
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), psoriasis is a long-lasting immune-mediated disease that can cause inflamed, scaly patches on the skin. The condition can also affect areas such as the scalp and nails. Its presence does not automatically explain an abnormal blood count.
The relationship depends on the type of psoriasis, the person's overall health, and whether another condition is present. Someone with ordinary plaque psoriasis may have a white blood cell count within the laboratory's expected range, while an elevated count in another person may reflect a separate infection, medication effect, or inflammatory process.
Why might white blood cells be elevated in someone with psoriasis?
White blood cells, also called leukocytes, help the body respond to infections, tissue injury, and other threats. A higher-than-expected count is known as leukocytosis. Psoriasis is one part of the person's medical picture, but several other factors may help explain the result.
1. Inflammation related to psoriasis
Inflammatory conditions can sometimes be associated with a higher white blood cell count. Because psoriasis involves immune-driven inflammation, it may be relevant when a healthcare professional reviews the result. However, an elevated count alone cannot establish how active the psoriasis is or prove that psoriasis caused the change.
2. An infection occurring at the same time
Infections are an important possible explanation for a higher white blood cell count. A respiratory infection, a skin infection, or another illness may occur alongside psoriasis. Some infections can also trigger a psoriasis flare, so worsening skin symptoms and an elevated count may occur around the same time without the psoriasis itself being the main cause of the blood result.
According to MedlinePlus, a high white blood cell count can be associated with bacterial or viral infections, inflammatory conditions, allergic reactions, and other medical problems. The blood test helps guide an evaluation, but it cannot identify the cause on its own.
3. Medicines and other factors
Some medicines can affect white blood cell levels. Corticosteroids, for example, can raise the count. Other possible influences include smoking, physical or emotional stress, recent injury, and pregnancy. These factors are especially relevant when a blood test is performed during an illness or after a change in medication.
- Medication changes: Tell your healthcare professional about prescription medicines, injections, and recently started or stopped treatments.
- Recent illness: Mention a recent infection, fever, surgery, or injury that might help explain the result.
- Smoking and stress: Both can affect white blood cell levels and may be relevant to the interpretation.
- Other health conditions: Inflammatory disorders and, less commonly, blood or bone marrow diseases may also cause leukocytosis.
Do not stop a prescribed medicine or change your psoriasis treatment simply because a blood test shows an elevated count. A healthcare professional can assess whether a medication is a possible contributor and determine whether any adjustment is appropriate.
Does the type of psoriasis make a difference?
Yes. It is particularly important to distinguish ordinary plaque psoriasis from generalized pustular psoriasis, a rare and potentially serious form of the condition. Generalized pustular psoriasis can cause widespread pus-filled skin bumps and affect the body beyond the skin. Abnormal blood tests, including changes in white blood cell levels, may occur during an episode.
The Cleveland Clinic explains that healthcare professionals may use blood tests to assess white blood cell levels and other possible complications when generalized pustular psoriasis is suspected. The results must be interpreted alongside the skin findings, symptoms, examination, and overall health.
Widespread pustules accompanied by fever or chills require immediate medical attention. The American Academy of Dermatology (AAD) identifies this combination as a warning sign of potentially life-threatening generalized pustular psoriasis. Do not wait for a routine blood test appointment if these symptoms occur.
How do doctors investigate a high white blood cell count?
The next step depends on how elevated the result is, whether it has occurred before, and what other findings are present. A healthcare professional will usually review the complete blood count (CBC), relevant symptoms, medical history, and medications. They may compare the result with previous tests to determine whether the change is new, persistent, or returning toward the expected range.
Reviewing the white blood cell differential
A white blood cell differential measures the different types of white blood cells rather than looking only at their total number. These include neutrophils, lymphocytes, monocytes, eosinophils, and basophils. The pattern can provide useful clues because different types of cells are involved in different immune responses.
According to MedlinePlus's explanation of the blood differential test, the test can help healthcare professionals investigate infections, immune system conditions, and blood disorders. The differential is only one part of the assessment; it does not establish a diagnosis by itself.
Checking for other causes
Depending on the findings, the clinician may examine the skin for signs of infection, ask about recent illnesses, or request additional blood tests. A repeat CBC may be appropriate to see whether the count remains elevated. Further testing is guided by the initial results and the person's overall clinical picture rather than being necessary for everyone.
The expected white blood cell range can differ among laboratories because of their methods and reporting standards. The result should therefore be interpreted using the reference interval on the report, the pattern of individual cell types, and other relevant findings.
What should you do if you have psoriasis and a high WBC count?
Arrange a review with your healthcare professional if an elevated count has been reported, particularly if it persists, increases on repeat testing, or appears alongside new symptoms. Share the full laboratory report and details of your psoriasis, recent illnesses, and current medicines. This information can help determine whether the change may be related to inflammation, infection, treatment, or another condition.
Seek prompt medical assessment if you develop fever, chills, worsening skin pain, or spreading redness and warmth around damaged skin. These symptoms may indicate an illness or infection that needs treatment. Widespread pus-filled bumps with fever or chills warrant immediate medical care because of the risk associated with generalized pustular psoriasis.
If the high count is unexpected but you feel well, it does not necessarily indicate a serious disease. However, it should not be dismissed solely because you have psoriasis. The appropriate follow-up may range from reviewing recent circumstances to repeating the blood test or investigating a specific concern.
Can treating psoriasis lower a high white blood cell count?
The answer depends on what is causing the elevated count. If psoriasis-related inflammation contributes to the change, controlling the skin condition may be relevant. If an infection, a medicine, or another health problem is responsible, addressing that cause may be more important. There is no single psoriasis treatment that can be expected to lower every elevated white blood cell count.
Psoriasis treatment should be selected according to the type of disease, the areas affected, symptom burden, other medical conditions, and possible treatment risks. A clinician may coordinate care between dermatology and primary care or another specialty if the blood result needs a separate investigation.
The key point: Psoriasis and a high white blood cell count can occur together, but the blood result is not proof that psoriasis is responsible. Reviewing the cell differential, recent illnesses, medications, and changes over time helps healthcare professionals decide what the result means and whether further evaluation is needed.