A serious white blood cell (WBC) count is generally considered to be significantly above or below the normal range, depending on the underlying cause. While labs set their own reference ranges, a count of more than 11,000 WBCs per microliter of blood in adults is often considered high. A low WBC count can also be serious, especially if it's drastically low and impacts the body's ability to fight infection.
Understanding High WBC Counts (Leukocytosis)
A high WBC count, or leukocytosis, can be triggered by various factors, including:
- Infection: The body produces more WBCs to fight infection.
- Injury: Trauma can lead to an increase in WBCs.
- Inflammation: Conditions causing inflammation, such as autoimmune diseases, can elevate WBC counts.
- Cancer: Certain types of cancer, such as leukemia, can significantly increase WBC production.
While a high WBC count can be a normal response to infection or injury, it can indicate a more serious underlying condition like leukemia (as noted in multiple sources like Cleveland Clinic and Patient Power).
Understanding Low WBC Counts (Leukopenia)
Conversely, a low WBC count, or leukopenia, is also serious because it compromises the immune system’s ability to fight infection. A critically low neutrophil count (a type of WBC), fewer than 500 neutrophils per microliter of blood, is known as severe neutropenia (MedlinePlus). This severely weakens the body's defense against infections, making even minor injuries risky. (Mayo Clinic)
Determining Severity
The severity of an abnormal WBC count isn't solely determined by the number itself. The cause of the abnormality and the individual's overall health significantly impact the seriousness. A high WBC count caused by a simple infection is less serious than one caused by leukemia. Similarly, the impact of low WBC counts is highly dependent on the reason for the decrease and the individual's general health. The context and other symptoms are crucial for a proper diagnosis.
Some studies even highlight the limited usefulness of an abnormal WBC count alone for diagnosis. For example, in some cases, an abnormal WBC count may not necessarily indicate serious bacterial infections (PubMed).
