Mean Corpuscular Volume

Mean Corpuscular Volume (MCV) offers valuable insights into red blood cell characteristics and potential underlying health conditions. 

This section provides an overview of MCV, highlighting its significance as part of routine blood studies.

Mean Corpuscular Volume (MCV) is a measurement that reflects the average volume or size of red blood cells (RBCs) in a blood sample. It informs various aspects of hematologic health, including RBC morphology and the presence of certain blood disorders or deficiencies.

In blood tests, MCV is typically reported as part of a complete blood count (CBC), which provides a comprehensive assessment of different blood cell types and their characteristics. 

Understanding MCV values aids healthcare providers in diagnosing and monitoring a wide range of medical conditions, from anemias to nutritional deficiencies and systemic diseases.

The interpretation of MCV levels requires consideration of various factors, including patient demographics, medical history, and concurrent laboratory findings. 

Changes in MCV can indicate alterations in RBC size, which may signify underlying pathology or physiological changes.

Understanding Mean Corpuscular Volume

Definition and Significance of MCV in Complete Blood Counts: What is Mean Corpuscular Volume?  [3.]

Mean Corpuscular Volume (MCV) is typically ordered as part of a complete blood count, or CBC.  This test is commonly run as a part of routine blood work.  

The MCV measures the average size and volume of red blood cells.  

As a laboratory parameter indicating the average size and volume of red blood cells (RBCs), it serves as a valuable tool in diagnosing anemia by helping to identify its underlying cause. 

MCV is calculated by multiplying the percent hematocrit by ten and then dividing it by the erythrocyte count. 

Alongside hemoglobin and hematocrit levels, MCV assists in classifying anemia into three types: 

• Microcytic anemia (MCV below the normal range, or smaller than normal RBCs)
• Normocytic anemia (MCV within the normal range, or RBCs of expected size)
• Macrocytic anemia (MCV above the normal range, or larger than normal RBCs) 

Additionally, MCV plays a role in determining the Red Blood Cell Distribution Width (RDW), providing further insights into the characteristics of anemia.

MCV and Anemias  [3.]

It is helpful to understand the different types of anemia identified by alterations in MCV values as part of a CBC.  

Microcytic anemia

Characterized by smaller-than-normal erythrocytes, with an MCV measure under 80 fL (normal range: 80 to 100 fL). 

It is often associated with conditions such as chronic iron deficiency anemia, anemia of chronic disease, sideroblastic anemia, and thalassemias.

Normocytic anemia

Hemoglobin and hematocrit levels are low, but MCV falls within the normal range of 80 to 100 fL. Subtypes include hemolytic and non-hemolytic forms, with causes ranging from intravascular and extravascular hemolysis to conditions like anemia of chronic disease, early iron deficiency anemia, aplastic anemia, and certain infections. Additional CBC parameters help further characterize the specific type of anemia.

Macrocytic anemia 

Involves larger-than-normal red blood cells, with an MCV over 100 fL. Further categorized as megaloblastic or non-megaloblastic, depending on DNA synthesis impairment. 

Megaloblastic anemia is commonly linked to folate or vitamin B12 deficiency, while non-megaloblastic anemia can result from hepatic insufficiency, chronic alcoholism, or Diamond-Blackfan anemia.

Laboratory Testing for Mean Corpuscular Volume (MCV)

Procedure for MCV Test

The MCV test is typically performed as part of a complete blood count (CBC) analysis. During the procedure, a small sample of blood is drawn from a vein in the arm using a needle. The blood sample is then sent to a laboratory for analysis. 

In the laboratory, automated hematology analyzers measure the size variation of red blood cells and calculate the MCV value.

Preparation for MCV Test

No special preparation is usually required for the MCV test. Patients can typically eat and drink normally before the test and do not need to fast. 

Related Biomarkers to Assess Alongside MCV in Blood Tests

In addition to MCV, other hematologic parameters may be assessed alongside MCV to provide a comprehensive evaluation of hematologic status. These markers are all typically included as part of a CBC, providing a comprehensive assessment of red and white blood cell health.

Related biomarkers that inform red blood cell health include

• Hemoglobin concentration
• Hematocrit
• Red blood cell distribution width (RDW)
• Mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC)

Assessment of these parameters alongside MCV helps clinicians further characterize RBC morphology and identify potential underlying abnormalities.

Clinical Implications of Mean Corpuscular Volume  [3.]

Clinical Significance of High MCV: What Does High Mean Corpuscular Volume (MCV) Mean?

High MCV levels, known as macrocytosis, occur when red blood cells are larger than normal.  A high MCV level indicates macrocytic anemia.  

Causes of macrocytic anemia include:

Megaloblastic anemia: 

Results from deficiencies in folate or vitamin B12, which are essential for proper pyrimidine synthesis and erythrocyte division.  Deficiencies can disrupt normal erythropoiesis, causing larger-than-normal RBCs.  

Non-megaloblastic anemia: 

Associated with liver disease, which compromises lipid production and affects the integrity of erythrocyte membranes. Chronic alcoholism or the use of certain medications including chemotherapeutic agents can also lead to impaired folate absorption, contributing to macrocytic anemia.

High MCV may also be observed in conditions characterized by increased RBC production, such as hemolytic anemias and recovery from acute blood loss.

Management of High MCV

The presence of high MCV levels warrants clinical attention and further evaluation to determine the underlying etiology. 

Treatment strategies for elevated MCV levels focus on addressing the specific cause or contributing factors. 

This may include supplementation with vitamin B12 or folate for nutritional deficiencies, management of underlying liver disease, discontinuation of offending medications, or initiation of appropriate therapy for hematologic disorders. 

Close monitoring of MCV levels and clinical response to treatment is essential for optimizing patient outcomes and ensuring resolution of macrocytosis.

Clinical Significance of Low MCV: What Does Low Mean Corpuscular Volume Mean?

Low Mean Corpuscular Volume (MCV) levels are known as microcytosis.

Causes of microcytosis include: 

‍Iron deficiency anemia

Caused by a deficiency in iron, necessary for heme synthesis, resulting in defective protoporphyrin rings and smaller erythrocytes.

‍Anemia of chronic disease

Occurs due to increased hepcidin levels in response to inflammation, leading to decreased iron absorption and trapping of iron in macrophages, resembling iron deficiency anemia.

Sideroblastic anemia

Can be secondary to lead poisoning, characterized by defective heme synthesis due to impaired iron incorporation into protoporphyrin rings.

Thalassemias 

Result from mutations in the alpha or beta globin chains, disrupting hemoglobin synthesis and leading to microcytic erythrocytes.

Clinical Implications and Management of Low MCV

The presence of low MCV levels warrants clinical assessment and further investigation to determine the underlying etiology. 

Treatment strategies for microcytosis focus on addressing the specific cause or contributing factors. This may involve iron supplementation for iron deficiency anemia, management of underlying chronic diseases or heavy metal exposure, or genetic counseling for hereditary disorders.

Regular monitoring of MCV levels and response to treatment is essential for optimizing patient outcomes and ensuring resolution of microcytosis.

Diet and Lifestyle Factors for Red Blood Cell Health

As a vital marker of red blood cell health, various diet and lifestyle factors may support healthy MCHC levels.

Dietary Factors

Iron-rich foods: Include sources such as lean meats, poultry, fish, legumes, tofu, nuts, seeds, and fortified cereals to support iron absorption and hemoglobin synthesis.

Vitamin B12 sources: Consume foods like fish, shellfish, meat, poultry, eggs, dairy products, and fortified plant-based foods to support erythropoiesis and red blood cell production.  [6.]

Folate-rich foods: Incorporate leafy green vegetables, legumes, citrus fruits, fortified grains, and liver into your diet to support DNA synthesis and red blood cell maturation.  [4.]

Vitamin C-rich foods: Pair iron-rich foods with sources of vitamin C, such as citrus fruits, strawberries, kiwi, bell peppers, and broccoli, to enhance iron absorption.  [2.]

‍Hydration: Drink an adequate amount of water daily to maintain proper blood volume and circulation, which supports red blood cell function.

Avoid excessive alcohol consumption: Excessive alcohol intake can impair red blood cell production and lead to anemia.  [1.]

Balanced diet: Consume a well-balanced diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats to provide essential nutrients for overall health and red blood cell production.

Lifestyle Factors

Regular exercise: Engage in moderate-intensity aerobic exercise and strength training to stimulate red blood cell production and improve oxygen delivery to tissues.  [7.]

Anti-inflammatory lifestyle: Avoid dietary and lifestyle habits including processed food, sleep deprivation, smoking or excessive alcohol, and excessive stress as inflammation damages red blood cell health and function.  [5.]

Maintain a healthy weight: Aim for a healthy body weight through balanced nutrition and regular physical activity to support optimal blood circulation and red blood cell production.

Avoid smoking: Smoking can impair oxygen delivery to tissues and damage blood vessels, negatively affecting red blood cell health.  [8.]

Regular medical check-ups: Visit your healthcare provider regularly for routine screenings and assessments to detect and address any underlying health conditions that may affect red blood cell health.

Testing Options

Click here for a list of testing options to assess MCV as part of a CBC.