WBC 0.8 x10³/µL

What 0.8 x10³/µL means

A white blood cell count of 0.8 x10³/µL is profoundly low — below 1.0, virtually every lab treats this as a critical value, and it usually means infection-fighting neutrophils are nearly absent (agranulocytosis).

At counts under 1.0, the absolute neutrophil count is almost always in the severe range (below 0.5), which carries the highest infection risk of any level. The body has essentially lost its frontline defense against bacteria and fungi, and infections can develop and spread within hours — often without the usual pus, swelling, or redness, because there are too few white cells left to produce them. Counts this low are most often seen at the low point after chemotherapy, with drug-induced agranulocytosis, or with bone marrow failure, and they require emergency-level attention: any fever at this count is treated as a medical emergency (febrile neutropenia).

Most US labs use roughly 4.5 to 11.0 x10³/µL as the adult reference range (the convention MedlinePlus cites), though some set the lower limit at 4.0 and the upper limit at 10.0 or 10.5. Critical-value cutoffs also vary by lab: below about 1.0–2.0 and above about 30–50 are the alarm thresholds most US laboratories use.

Common causes

• Chemotherapy at its nadir — counts typically bottom out 7–14 days after a treatment cycle
• Drug-induced agranulocytosis from medications such as clozapine, methimazole, propylthiouracil, sulfasalazine, and certain antibiotics
• Aplastic anemia and other bone marrow failure syndromes
• Acute leukemia or other cancer crowding out normal marrow production
• Overwhelming infection (sepsis) consuming white cells faster than the marrow can replace them
• Radiation therapy or radiation exposure affecting large areas of bone marrow
• Advanced HIV or other severe infections suppressing the marrow

Symptoms that can go with it

• Fever, chills, or shaking rigors — often the first and only warning of infection
• Severe sore throat or painful mouth ulcers, a classic sign of agranulocytosis
• Infections that worsen rapidly, sometimes with little visible redness or pus
• Profound fatigue or feeling suddenly and severely unwell
• Sometimes no symptoms at all until an infection takes hold

Sensible next steps

1. Treat this as an emergency result: call the clinician who ordered the test or your care team immediately — labs phone counts this low to the ordering clinician as a critical value
2. Go to the emergency department now if you have a fever of 100.4°F (38°C) or higher, chills, or feel unwell in any way — febrile neutropenia is a medical emergency treated with IV antibiotics without delay
3. If you cannot reach your clinician within a few hours, go to the ER even without symptoms, and bring your lab report
4. Bring a complete list of every medication and supplement — drugs such as clozapine and methimazole are common and reversible causes, but only your clinicians should decide what to stop
5. Until you are seen, wash hands strictly, avoid crowds and anyone who is sick, and skip raw or undercooked foods
6. Expect same-day repeat testing with a differential, likely hematology involvement, and possibly hospital admission and growth-factor injections while the cause is found and treated