An MCV blood test measures the average size of your red blood cells. It is typically included as part of a complete blood count (CBC), a broader panel of tests that assesses various blood components. The MCV result helps healthcare providers understand your red blood cell characteristics.
What MCV Measures
MCV, or Mean Corpuscular Volume, quantifies the average volume of red blood cells. Red blood cells, also known as erythrocytes, transport oxygen from your lungs to tissues and organs. The size of these cells directly impacts their efficiency in carrying oxygen. If red blood cells are too small or too large, it can affect how effectively oxygen is delivered, potentially indicating underlying health conditions.
Why an MCV Test is Performed
An MCV test is often performed during routine health check-ups. Doctors may order an MCV test for symptoms suggesting anemia, such as fatigue, weakness, or pale skin. It also helps in identifying nutritional deficiencies, such as low iron, vitamin B12, or folate, which are important for healthy red blood cell production. Beyond diagnosis, the MCV test is used to monitor certain chronic conditions, like liver disease or kidney disease, and to evaluate the effectiveness of treatments for blood disorders.
Interpreting MCV Test Results
Understanding MCV test results involves comparing your value to a standard reference range. For adults, a normal MCV falls between 80 and 100 femtoliters (fL). Values outside this range indicate variations in red blood cell size.
Low MCV (Microcytic)
When the MCV is below 80 fL, red blood cells are smaller than average, a condition known as microcytosis. This suggests red blood cells may contain less hemoglobin, the protein responsible for oxygen transport. Common causes include iron deficiency anemia, a widespread form of anemia, and thalassemia, an inherited blood disorder affecting hemoglobin production. Anemia of chronic inflammation, lead poisoning, and sideroblastic anemia can also lead to microcytic red blood cells.
High MCV (Macrocytic)
An MCV greater than 100 fL indicates red blood cells are larger than average, a condition called macrocytosis. This can occur due to impaired DNA synthesis during red blood cell formation. A high MCV is often linked to deficiencies in vitamin B12 or folate, both necessary for proper red blood cell development. Other causes can include liver disease, excessive alcohol consumption, certain medications, and some bone marrow dysfunctions. If your MCV results are outside the typical range, further medical evaluation is necessary to determine the underlying cause.