Can Genes Influence Your Metamyelocyte Count

Disclaimer: This article is for informational purposes only and is not intended to diagnose any conditions. LifeDNA does not provide diagnostic services for any conditions mentioned in this or any other article.

Have you ever received a blood test result that included a term you didn’t recognize, like “metamyelocyte count”? While it may sound intimidating, understanding this may provide valuable insights into your overall health. Recognizing its significance may help you gain insight into your body’s response to stress and disease, which may potentially lead to more informed decisions about your health care.

What is Metamyelocyte Count?

Metamyelocytes are immature neutrophils in the early stages of white blood cell development, which play an important role in your immune system by helping your body fight infections. In a healthy individual, metamyelocytes are typically confined to the bone marrow where blood cells are produced and do not appear in the bloodstream. However, under certain conditions—such as infection, inflammation, or stress—the body may release immature white blood cells, including metamyelocytes, into the bloodstream.

The metamyelocyte count refers to the number of these immature cells found in a blood sample. In a routine blood test, metamyelocytes are not usually present in the blood. If they are detected, it might suggest that the bone marrow is producing white blood cells rapidly in response to an issue, such as an infection or another underlying condition. Doctors use the metamyelocyte count as part of a broader blood test to help diagnose and monitor various health conditions.

How Do You Measure Metamyelocyte Count?

The metamyelocyte count is measured as part of a routine blood test called a complete blood count (CBC) with a differential (including a breakdown of different white blood cell types). This test provides doctors with a detailed overview of your blood’s composition, particularly focusing on the various types of cells present, including those involved in your immune response.

Here’s what you can expect if your doctor orders this test:

Getting a Blood Sample: A small amount of blood is drawn, usually from a vein in your arm. This process is quick and typically done during a visit to your doctor or at a lab.
Analyzing the Blood: Once your blood sample reaches the lab, it iss analyzed to determine the types and quantities of cells present. The lab specifically looks for any immature white blood cells, such as metamyelocytes, which are not normally found in circulating blood.
Understanding the Results: Normally, metamyelocytes are only found in the bone marrow, not in the bloodstream. If they show up in your blood, it could be a sign that your body is responding to a particular condition, such as an infection, inflammation, or another type of stress.
What the Results Mean for You: If your metamyelocyte count is higher than normal, your doctor might look into other tests or ask about symptoms you’re experiencing. This helps them figure out if there’s an underlying condition that needs attention.

What is the Normal Metamyelocyte Count?

While genetic factors play a role in the normal proportions of various blood cells, the specific genetic variants influencing metamyelocyte counts are not well-defined. However, the normal levels of metamyelocytes may vary. While their presence in the bloodstream is generally abnormal, their presence in the bone marrow is part of the normal blood cell maturation. Understanding this helps in assessing whether their presence indicates a health issue.

Presence in Blood

The normal metamyelocyte count is zero when measured in the bloodstream. If metamyelocytes are detected in the bloodstream, it is generally considered abnormal and may indicate that the body is responding to an underlying condition. The presence of metamyelocytes in the blood may need further examination to determine the cause and assess the need for treatment.

In Bone Marrow

In the bone marrow, metamyelocytes are a normal part of the development process for white blood cells. While there isn’t a specific “normal” count for metamyelocytes in the bone marrow due to variations in individual health and age, their presence is expected as they mature into more specialized white blood cells. The bone marrow typically contains a range of immature white blood cells, including metamyelocytes, which are part of the normal hematopoiesis (blood cell formation) process.

What Causes High or Low Metamyelocyte Count?

High Metamyelocyte Count

A high metamyelocyte count means that there are more of these immature white blood cells in your bloodstream than usual. This is not typical, as metamyelocytes should normally only be found in the bone marrow. Elevated levels can suggest several potential issues:

Infection: The body may release immature white blood cells into the bloodstream while fighting an infection.
Inflammation: Chronic inflammation or conditions causing ongoing stress to the body may lead to increased metamyelocyte production.
Bone Marrow Disorders: Conditions like chronic myelogenous leukemia (CML), myelodysplastic syndromes (MDS), or other myeloproliferative disorders may lead to an increased release of immature cells, including metamyelocytes, into the bloodstream.
Severe Physical Stress: Physical stress, severe illness, or trauma can also cause a temporary increase in metamyelocyte count as the body mobilizes its immune defenses.
Toxic Exposure: Exposure to certain toxins, chemotherapy, or radiation may damage the bone marrow, leading to an increased release of immature cells.

Low Metamyelocyte Count

A low metamyelocyte count is rarely discussed because metamyelocytes are typically not present in the bloodstream under normal conditions. Their presence is expected primarily in the bone marrow, where they develop as part of the neutrophil maturation process. However, if their count is unusually low in the bone marrow, it may signal an underlying issue affecting bone marrow function.

For example, aplasia or dysfunction of the bone marrow can impair the production of metamyelocytes and other essential blood cells.

Aplastic Anemia: Aplastic anemia is a serious condition in which the bone marrow fails to produce enough blood cells, including white blood cells (WBCs) and their precursors, such as metamyelocytes. In this scenario, a low metamyelocyte count reflects the marrow’s inability to generate and release sufficient immune cells. This deficit weakens the body’s immune response, leaving it vulnerable to infections and other complications.
Certain Types of Leukemia: In some forms of leukemia, particularly those where the bone marrow becomes crowded with abnormal, cancerous cells, the production of normal blood cells is significantly hindered. As a result, the number of healthy precursor cells, including metamyelocytes, may be lower than expected. A bone marrow biopsy in these cases often reveals a diminished count of metamyelocytes, indicating that the marrow’s capacity to produce normal blood cells is compromised.
Chronic Diseases: Long-standing chronic illnesses, such as autoimmune diseases, chronic infections, or severe inflammatory disorders, can lead to bone marrow suppression. This results in a reduced production of all blood cell types, including neutrophil precursors like metamyelocytes.
Malnutrition: Nutritional deficiencies, particularly those affecting vitamins and minerals essential for blood cell production (e.g., vitamin B12, folate, or iron), can impair the bone marrow’s ability to produce white blood cells. In cases of severe malnutrition, a bone marrow examination may reveal fewer immature cells, including metamyelocytes.

When Should Metamyelocytes Be Detected in Blood?

Metamyelocytes should not typically be present in peripheral blood. However, they may appear in the bloodstream under certain conditions, such as:

Severe Infections: When the body requires an urgent response to infection, the bone marrow may release immature cells like metamyelocytes into the blood.
Hematologic Disorders: Conditions affecting the bone marrow, such as leukemia or myeloproliferative disorders, may result in the release of metamyelocytes into circulation.

Immature Neutrophils as Indicators of Sepsis

Myelocytes and metamyelocytes, as well as other immature neutrophils are emerging as important biomarkers for assessing infection severity and predicting outcomes. Band cells, another type of immature neutrophil, signal severe infections like sepsis when present in high numbers—a condition known as a “shift to the left.” Elevated band cell levels are linked to poorer sepsis outcomes.

Research has demonstrated that high percentages of band cells are associated with poorer outcomes in sepsis. Specifically, a groundbreaking study found that band cells had a sensitivity of 84% and a specificity of 71% for detecting definite sepsis at an 8.5% cutoff point. This makes band cells a valuable tool for differentiating between sepsis and non-infectious systemic inflammatory response syndrome (N-I SIRS).

Myelocytes and metamyelocytes, though less commonly monitored, also provide critical prognostic information. The same study discovered that patients with up to 40% of these cells in their blood had significantly higher mortality rates. Specifically, patients who died within the first week of ICU stay had a median of 9% myelocytes and metamyelocytes in their blood, compared to much lower levels in those who survived longer.

The presence of immature neutrophils in the blood, particularly in ICU settings, is associated with higher mortality risk, highlighting their potential as valuable markers in managing severe infections. Monitoring these cells aids in distinguishing between systemic inflammatory response syndrome (SIRS) and sepsis, thus guiding treatment and improving patient management.

Non-Genetic Factors Influencing Metamyelocyte Count

Several non-genetic factors can influence the metamyelocyte count in your blood. These factors often relate to the body’s response to various conditions or stressors. Here’s how they might affect your metamyelocyte levels:

Infections: During infections, especially the severe ones with bacterial origin like sepsis, the body releases immature white blood cells, such as metamyelocytes, into the bloodstream. This response is part of the immune system’s effort to rapidly combat the invading pathogens.
Inflammation: Chronic inflammation or inflammatory diseases such as rheumatoid arthritis or inflammatory bowel disease, can stimulate the bone marrow to produce more white blood cells, including metamyelocytes, as the body attempts to manage and repair affected tissues.
Stress: Physical or emotional stress can lead to an increase in the production of white blood cells, including metamyelocytes, as part of the body’s heightened immune response. For example, severe trauma or surgery can temporarily elevate metamyelocyte counts.
Bone Marrow Disorders: Disorders affecting the bone marrow, such as leukemia or myelodysplastic syndromes, can result in the abnormal production and release of immature cells like metamyelocytes into the bloodstream. In acute myeloid leukemia (AML), this process is particularly pronounced, leading to elevated metamyelocyte levels.
Medications: Certain medications, such as granulocyte colony-stimulating factor (G-CSF) used during chemotherapy, can stimulate bone marrow activity and increase metamyelocyte counts as they enhance white blood cell production.
Nutritional Deficiencies: While nutritional deficiencies are less directly linked to metamyelocyte counts, they can impact overall blood cell health. Deficiencies in essential nutrients like vitamin B12 or folate may indirectly affect white blood cell production by impairing bone marrow function.
Systemic Diseases: Systemic diseases, such as chronic kidney disease or liver disease, can alter bone marrow function and lead to changes in blood cell counts, including metamyelocytes. Chronic kidney disease, for instance, may influence the production of immature cells in the blood.

Summary

Metamyelocytes are immature white blood cells in early stages of development, maturing into neutrophils which play a crucial role in the immune system by fighting infections.
These immature cells are normally found only in the bone marrow.
The metamyelocyte count is assessed via a complete blood count (CBC) with a differential, which provides a detailed breakdown of different white blood cell types. Typically, metamyelocytes are absent from the bloodstream.
In a healthy individual, the normal metamyelocyte count in the blood is zero. Their presence in the bloodstream suggests a potential health issue and may necessitate further investigation.
In the bone marrow, metamyelocytes are a normal part of the blood cell maturation process, with no specific “normal” count due to variability among individuals.
A high metamyelocyte count can indicate various issues, including infections, chronic inflammation, bone marrow disorders, severe physical stress, or toxic exposure. Elevated levels, especially in blood, are important for diagnosing and monitoring health conditions.
A low metamyelocyte count is less frequently discussed but may suggest bone marrow problems or chronic diseases affecting white blood cell production.
Metamyelocytes, along with other immature neutrophils like band cells, are used to assess the severity of infections and patient prognosis. High levels of band cells often signal severe infections such as sepsis and can differentiate between sepsis and non-infectious systemic inflammatory response syndrome (N-I SIRS).
Elevated myelocyte and metamyelocyte counts are associated with poorer outcomes in ICU settings and can help predict patient prognosis. High levels correlate with a higher risk of mortality.