Neutropenia
A low count of neutrophils, the main infection-fighting white cell. Mild neutropenia is often harmless, but a significantly low count weakens defence against bacterial infection — and a low count with a fever, especially after chemotherapy, is a medical emergency.
What it is
Neutropenia is a reduced number of neutrophils, the white cells that form the first line of defence against bacterial and fungal infection. Its importance depends entirely on how low the count is and why. Mild neutropenia is common and often benign — it can follow a viral infection, be a harmless lower baseline in some healthy people (ethnic benign neutropenia), or be a minor drug effect. A significantly low count, however, leaves the body poorly defended, and the risk of serious infection rises steeply as the count falls. The most important cause is treatment that suppresses the bone marrow — chemotherapy above all — but neutropenia can also come from certain medications, autoimmune conditions, severe infections, vitamin B12 or folate deficiency, and bone-marrow disorders. The single most critical scenario is neutropenia with a fever, which signals possible severe infection needing immediate treatment.
Key lab markers
- Neutrophil count (absolute) — defines and grades the neutropenia; the lower it is, the higher the infection risk.
- Full blood count — checks whether other cell lines (haemoglobin, platelets) are also low, which points toward a marrow problem.
- Blood film — examined for clues to the cause.
- Vitamin B12 and folate — deficiency can lower the count.
- Repeat count — a single mildly low value is often rechecked, as it can be transient.
- Further tests (marrow, autoimmune, viral) — if the neutropenia is significant, persistent or unexplained.
Symptoms
- Often none when mild — found on a blood test
- Frequent or severe infections when the count is significantly low
- Mouth ulcers, sore throat, gum infections
- Fever — the key warning sign, especially after chemotherapy
- Skin infections that are slow to heal The danger is not a symptom of neutropenia itself but the infections it allows.
Related lab panels
When to discuss with a doctor
The response to neutropenia depends on how low the count is and the setting. A mild, incidental neutropenia in a well person is often simply rechecked and monitored, sometimes after reviewing medications or checking B12 and folate. A significantly low count needs prompt evaluation for the cause. Crucially, anyone with neutropenia — especially during or after chemotherapy — who develops a fever must seek emergency care immediately, because neutropenic sepsis can be life-threatening and the usual signs of infection may be muted. Mediora.AI flags a low neutrophil count and whether other cell lines are affected; the assessment and, when needed, urgent treatment belong with your doctor.