An ANC blood test measures the absolute neutrophil count in your blood, telling you how many neutrophils you have per microliter. Neutrophils are the most abundant type of white blood cell, and their primary job is fighting off bacterial and fungal infections. A normal ANC falls between 1,500 and 8,000 cells per microliter. When your count drops below 1,500, you’re considered neutropenic, meaning your body has a reduced ability to fight infections.
What Neutrophils Do and Why They’re Counted Separately
Your total white blood cell count includes several different cell types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each plays a different role in immune defense. Neutrophils are the first responders. When bacteria enter a wound or an infection takes hold somewhere in your body, neutrophils rush to that site and destroy the invaders. They typically make up 50% to 70% of all white blood cells.
A total white blood cell count can look normal even when neutrophils specifically are dangerously low. That’s why doctors order the ANC separately. It gives a much more precise picture of your ability to fight common infections, which is especially important during cancer treatment, after organ transplants, or when evaluating unexplained fevers.
How ANC Is Calculated
ANC is part of a standard blood draw called a complete blood count (CBC) with differential. No special fasting or preparation is required. The lab measures your total white blood cell count and then identifies the percentage of those cells that are neutrophils.
The formula is straightforward: your white blood cell count multiplied by the percentage of neutrophils (both mature “segmented” cells and younger “band” cells), divided by 100. So if your white blood cell count is 8,000 and neutrophils make up 60% of that total, your ANC would be 4,800 cells per microliter. Many labs now report the ANC as an absolute number directly on your results, so you don’t need to calculate it yourself.
Normal Range and Severity Levels
A healthy ANC is generally 1,500 to 8,000 cells per microliter. Below 1,500, the condition is called neutropenia, and it’s graded by severity:
- Mild neutropenia: ANC between 1,000 and 1,500 cells per microliter. Infection risk is slightly elevated but still manageable.
- Moderate neutropenia: ANC between 500 and 1,000. Your immune defense is noticeably weakened.
- Severe neutropenia: ANC below 500. At this level, even minor bacteria that your body would normally handle easily can cause serious, potentially life-threatening infections.
One important nuance: these thresholds were established primarily in white populations. People of African, Middle Eastern, and Caribbean descent commonly have a baseline ANC between 1,000 and 1,500, a well-recognized variation called benign ethnic neutropenia. These individuals are not at increased infection risk despite technically falling below the standard cutoff. If you’re in one of these groups and your count consistently sits in that range with no history of unusual infections, it’s generally considered a normal variant rather than a medical problem.
What Causes a Low ANC
Chemotherapy is one of the most common reasons for a low ANC. Cancer treatments work by killing rapidly dividing cells, and the cells in your bone marrow that produce neutrophils divide quickly, making them collateral damage. Radiation therapy and bone marrow transplants have the same effect. For people undergoing cancer treatment, ANC is monitored closely because it determines whether the next round of chemotherapy can proceed on schedule or needs to be delayed.
Beyond cancer treatment, many other conditions can drive your count down. Viral infections, including hepatitis, HIV, COVID-19, chickenpox, and measles, can temporarily suppress neutrophil production. Autoimmune diseases like lupus and rheumatoid arthritis sometimes cause the immune system to attack its own neutrophils. Bone marrow disorders such as aplastic anemia and myelofibrosis impair the marrow’s ability to produce blood cells altogether.
Certain medications unrelated to cancer can also lower your ANC. Some antibiotics, antiviral drugs, anti-inflammatory medications, antipsychotics, and drugs for overactive thyroid are known to cause neutropenia as a side effect. Nutritional deficiencies in vitamin B-12, folate, or copper can also reduce production. In some cases, no cause is ever identified, a situation called chronic idiopathic neutropenia.
What Causes a High ANC
An elevated ANC, called neutrophilia, is most commonly caused by infection or inflammation. Bacterial infections in particular trigger a rapid surge in neutrophil production as your body mobilizes its defenses. You may also see a high count with chronic inflammatory conditions like inflammatory bowel disease, rheumatoid arthritis, or chronic hepatitis.
Not all causes are disease-related. Physical or emotional stress, vigorous exercise, cigarette smoking, obesity, surgery, and even temperature changes can temporarily push neutrophil counts higher. Pregnancy raises the count as well. In rare cases, a persistently elevated ANC can signal a blood cancer like leukemia, which is why an unexplained high count warrants follow-up.
Protecting Yourself With a Low ANC
If your ANC drops below 1,000, and especially below 500, everyday germs become a real threat. The CDC recommends several practical precautions during this vulnerable period. Wash your hands frequently, and avoid crowded places and contact with anyone who’s sick. Don’t share utensils, cups, or personal items like toothbrushes.
Food safety becomes more important than usual. Cook meat and eggs thoroughly, and wash raw fruits and vegetables carefully. Shower or bathe daily and use unscented lotion to keep your skin from cracking, since broken skin is an entry point for bacteria. Wear gloves when gardening or cleaning up after pets. Brush your teeth gently with a soft toothbrush to avoid creating sores in your mouth. Get a flu shot as soon as it’s available each season.
The most critical thing to watch for is fever. With a severely low ANC, a temperature of 100.4°F (38°C) or higher is treated as a medical emergency called febrile neutropenia. Your body may not be able to produce the usual signs of infection like redness, swelling, or pus, so fever can be the only warning sign that something dangerous is happening.
How ANC Guides Cancer Treatment Decisions
For people on chemotherapy, ANC acts as a gatekeeper. Most treatment protocols require a minimum ANC, often around 1,000 to 1,500, before administering the next cycle. If your count hasn’t recovered enough, your oncologist may delay treatment by a week or more, or reduce the dose for future cycles. These delays can be frustrating, but proceeding with a dangerously low ANC risks severe infection.
In some cases, doctors prescribe medications that stimulate the bone marrow to produce neutrophils more quickly, helping patients stay on schedule. Your ANC is typically checked with a blood draw before each chemotherapy session, and sometimes at the midpoint between cycles when counts tend to reach their lowest point, usually 7 to 14 days after treatment.