Low White Blood Cell Count: What It Means and What to Do Next
A low white blood cell (WBC) count, or leukopenia, means you have fewer of the cells that fight infection than the reference range. Quest's adult range is 3.8–10.8 thousand cells per microliter, but go by the range printed on your report. Common causes are a recent viral infection, medications, autoimmune conditions such as lupus, and low B12, folate or copper. Many healthy people of African, Middle Eastern or Caribbean ancestry have a naturally lower count, called Duffy-null associated neutrophil count, that carries no extra infection risk. What matters most is the absolute neutrophil count (ANC) on the differential.
What Causes Low White Blood Cell Count?
Viral Infections
Flu, COVID-19, mono, hepatitis and other viruses commonly lower the white count for a few weeks. It recovers on its own after the infection clears.
Duffy-Null Associated Neutrophil Count
A common inherited variant, most frequent in people of African, Middle Eastern or Caribbean ancestry, sets the normal neutrophil count lower. It is harmless and does not raise infection risk, but it is often flagged as low.
Medications
Chemotherapy is the best-known cause. Others include some antibiotics, antithyroid drugs (methimazole, propylthiouracil), clozapine, some anti-seizure drugs and immunosuppressants.
Autoimmune Conditions
Lupus, rheumatoid arthritis and other autoimmune diseases can lower white cells, sometimes as the first sign.
Nutrient Deficiencies
Low B12, folate or copper can lower white cells, often together with anemia. Copper deficiency is seen after weight-loss surgery or with very high zinc intake.
Alcohol and Liver Disease
Heavy drinking suppresses the marrow, and an enlarged spleen from liver disease traps white cells.
Severe Infection and HIV
Overwhelming infections such as sepsis can use up white cells faster than the marrow makes them. HIV lowers lymphocytes over time.
Bone-Marrow Disorders
Rarely, the marrow itself is not making enough cells, as in aplastic anemia, myelodysplastic syndrome or leukemia. Red cells and platelets are usually low too.
Associated Symptoms
What to Do Next
1. Retest to confirm
A single abnormal result should be confirmed with a repeat test. Temporary factors like stress, illness, or medications can affect results.
2. Related tests to consider
3. When to see a doctor
If your White Blood Cell Count is significantly abnormal, if you have severe symptoms, or if repeated results confirm the abnormality, consult a healthcare professional for appropriate evaluation and treatment.
Related Conditions
Frequently Asked Questions
This page is for informational purposes only and does not constitute medical advice. Consult a healthcare provider for interpretation of your results.
Content reviewed for accuracy by the JustLabs editorial team.