Low neutrophils and low lymphocytes mean two types of white blood cells that help fight infections are below the lab’s expected range. This can happen temporarily during or after an infection, or because of medicines, poor nutrition, immune conditions, or problems affecting the bone marrow. The result alone does not identify the cause. Doctors interpret the actual cell counts, symptoms, medicines, and whether levels stay low on repeat tests.
What do neutrophils and lymphocytes do?
Neutrophils and lymphocytes are two important types of white blood cells. Although both help protect the body from infection, they have different roles. Neutrophils respond quickly to many bacterial and fungal infections, while lymphocytes help coordinate immune responses and recognize specific germs, including viruses.
According to MedlinePlus, a blood differential test measures the amount or percentage of each type of white blood cell. Having low levels of both neutrophils and lymphocytes means that two parts of the body's immune defenses may be affected. The possible impact depends on how low the counts are, how long they remain low, and what is causing the change.
What can cause both neutrophils and lymphocytes to be low?
There is no single explanation for both counts being low. Sometimes, the change is temporary and occurs during an illness or after treatment with certain medicines. In other cases, a health condition affects the production, survival, or distribution of white blood cells.
Mayo Clinic identifies infections, certain medicines, cancer treatments, autoimmune diseases, bone marrow disorders, and nutritional deficiencies as possible causes of low neutrophils. Several of these factors can also be associated with low lymphocytes.
- Recent or current infections: Some viral illnesses can temporarily lower white blood cell counts. Certain serious bacterial infections, including sepsis, may also affect neutrophil and lymphocyte levels.
- Medicines and medical treatments: Chemotherapy and radiation therapy can reduce blood cell counts. Certain antibiotics, immune-suppressing medicines, and corticosteroids can also contribute to changes in white blood cells.
- Nutritional deficiencies: Inadequate nutrition and deficiencies of vitamin B12 or folate may interfere with the body's ability to produce healthy blood cells. Other nutritional deficiencies may also be relevant in some cases.
- Autoimmune conditions: Conditions such as lupus and rheumatoid arthritis can be associated with low white blood cell counts, including neutropenia or lymphopenia.
- Bone marrow or blood disorders: Less commonly, conditions such as aplastic anemia, myelodysplastic syndromes, leukemia, or lymphoma may affect the production of one or more types of blood cells.
These possibilities are not equally likely for every person. For example, a recent infection or a medicine may help explain a new change, while persistent low counts or abnormalities in other blood cells may require a broader evaluation. The pattern of results over time is often more informative than a single blood test.
Does having both counts low mean something serious?
Not necessarily. Both counts can be temporarily low, and the finding does not automatically mean that a person has a serious illness. However, the combination deserves attention because neutrophils and lymphocytes support different aspects of immune protection.
The degree of neutropenia is particularly important when assessing the risk of bacterial and fungal infections. The Merck Manual explains that infection risk increases when neutrophil counts become very low. The duration of the abnormality, the presence of other medical problems, and whether there are signs of infection also influence clinical decisions.
Low lymphocytes may also affect the immune system, depending on which lymphocyte types are reduced and how much their numbers have fallen. A brief decrease that improves after an illness is different from a persistent abnormality associated with recurrent infections or other changes in the blood count.
How should you interpret the numbers on your blood test?
A complete blood count with a differential, often called a CBC with differential, reports the different types of white blood cells. Results may include both percentages and absolute counts. This distinction matters because a low percentage does not always mean that the actual number of cells is below the expected range.
The absolute neutrophil count (ANC) measures the number of neutrophils in a given volume of blood. The absolute lymphocyte count (ALC) does the same for lymphocytes. Healthcare professionals use these values, along with the laboratory's reference ranges, to assess whether the counts are truly low and how significant the findings may be.
Reference ranges also depend on age and the laboratory performing the test. According to Cleveland Clinic, normal lymphocyte levels differ between adults and children, and interpretation in children depends on their age. Adult reference limits should therefore not automatically be applied to a child's results.
Doctors also check the total white blood cell count and other blood components, including red blood cells, hemoglobin, and platelets. If several types of blood cells are low together, the overall pattern may suggest a different explanation from an isolated decrease in neutrophils or lymphocytes.
What symptoms can occur when both counts are low?
Low counts do not always cause noticeable symptoms themselves. Symptoms may instead come from an infection or the condition responsible for the blood test changes. Depending on the situation, experiences may include:
- Fever, chills, or sweating.
- A sore throat, painful mouth ulcers, or other mouth problems.
- A new or worsening cough or shortness of breath.
- Burning or pain during urination.
- Redness, swelling, or increasing pain around a wound or area of skin.
- Infections that happen repeatedly or take longer than expected to improve.
These symptoms are examples of possible signs of infection, not a way to determine your blood cell counts. Some people with low counts have no symptoms, so the laboratory results and clinical assessment remain important.
When should you seek medical attention?
If you know your neutrophils are low and develop a fever, chills, or other signs of infection, seek prompt medical advice. A significant reduction in neutrophils can make infections more dangerous, and fever may be an important early warning sign.
If you are receiving chemotherapy, the Centers for Disease Control and Prevention (CDC) advises contacting your treatment team immediately for a temperature of 100.4°F (38°C) or higher. Do not wait for a routine appointment or until the next morning. Follow any specific emergency instructions provided by your cancer care team.
Even without symptoms, discuss the results with a healthcare professional if both counts remain low on repeat tests, the abnormalities are marked, other blood cell counts are also abnormal, or you have frequent or unusual infections. A new or worsening health problem also deserves timely evaluation.
How do doctors investigate low neutrophils with low lymphocytes?
Evaluation usually begins with reviewing the blood test and looking for possible explanations. Your healthcare professional may ask about recent infections, current and recently used medicines, supplements, nutritional intake, existing medical conditions, and previous blood test results. A physical examination may help identify signs of infection or another underlying problem.
Depending on the findings, the next steps may include:
- Repeating the CBC with differential: This helps determine whether the low counts persist or return toward the expected range.
- Reviewing absolute cell counts: The ANC and ALC help clarify the actual number of neutrophils and lymphocytes.
- Checking other blood cell results: Red blood cells, hemoglobin, and platelets may provide additional information.
- Ordering targeted tests: Depending on the history and examination, testing may look for an infection, vitamin deficiency, or an autoimmune condition.
- Considering specialist assessment: Persistent, unexplained abnormalities or changes affecting several blood cell types may require assessment by a hematologist, a doctor specializing in blood disorders. In selected cases, further tests may evaluate bone marrow function.
Not everyone needs every test. The choice depends on the degree of the abnormalities, how long they have been present, associated symptoms, and the results of the initial evaluation.
What happens if both counts remain low?
The next steps depend on the underlying cause. When low counts are related to a temporary infection, they may improve as the person recovers. If a medicine is responsible, the prescribing clinician may review the dose or consider an alternative when appropriate. Confirmed nutritional deficiencies or other underlying conditions may require specific treatment.
Do not stop prescribed medicines or start supplements solely because of an abnormal blood count. Some treatments are essential, and unnecessary changes may create other health risks. A healthcare professional can determine whether treatment is needed and when repeat blood testing is appropriate.
Overall, low neutrophils together with low lymphocytes are a finding that needs to be interpreted in context, rather than a diagnosis on its own. The actual counts, other blood test results, recent illnesses, medicines, and changes over time help determine whether the finding is temporary or needs further investigation.