MCV and MCHC are two measurements on a standard blood test called a complete blood count (CBC). MCV stands for mean corpuscular volume and tells you the average size of your red blood cells. MCHC stands for mean corpuscular hemoglobin concentration and tells you how densely packed with hemoglobin each red blood cell is. Together, they help identify different types of anemia and other blood disorders.
What MCV Measures
MCV is measured in femtoliters (fL), a unit of volume so small it’s only useful at the cellular level. The normal range for adults is 80 to 100 fL. A result in that range means your red blood cells are a normal size. Below 80 fL, your cells are considered small (microcytic). Above 100 fL, they’re considered large (macrocytic).
Red blood cell size matters because it reflects how well your body is producing hemoglobin, the protein that carries oxygen through your bloodstream. When something disrupts hemoglobin production, your red blood cells often shrink or swell in response. Your body actually prioritizes keeping hemoglobin concentration stable, even if that means sacrificing cell size. This is why iron deficiency causes cells to shrink: the body makes smaller cells to maintain hemoglobin density with less raw material available.
What MCHC Measures
MCHC measures the average concentration of hemoglobin within each red blood cell, expressed in grams per deciliter (g/dL). The normal range is 32 to 36 g/dL. Think of it as how “full” each cell is. A low MCHC means the cells are pale and dilute, carrying less oxygen-transporting hemoglobin per unit of volume. This is called hypochromia, and cells drop below 30 g/dL to reach that designation.
You might also see MCH on your blood work, which looks confusingly similar. The difference: MCH measures the total weight of hemoglobin in each cell, while MCHC measures the weight of hemoglobin relative to the cell’s volume. MCH tells you how much hemoglobin is in a cell. MCHC tells you how concentrated that hemoglobin is. MCHC is more useful for spotting certain conditions because it accounts for cell size.
What Low MCV Means
Small red blood cells point to problems with hemoglobin production. The most common cause by far is iron deficiency anemia. You can develop it from not getting enough dietary iron, from chronic blood loss (including heavy menstrual periods), or from conditions that block iron absorption in your gut. When your body lacks iron, it can’t build hemoglobin efficiently, and it compensates by making smaller cells.
Thalassemia, a group of inherited conditions affecting hemoglobin production, is another well-known cause. People with thalassemia traits often have a persistently low MCV that doesn’t respond to iron supplements, which is one way it gets distinguished from iron deficiency. A rare cause is sideroblastic anemia, where the bone marrow has iron available but can’t incorporate it into hemoglobin properly.
What High MCV Means
Large red blood cells typically result from problems with DNA synthesis during cell development. The two most common nutritional causes are vitamin B12 deficiency and folate (vitamin B9) deficiency. Without enough of these nutrients, developing red blood cells can’t divide normally in the bone marrow. They keep growing instead of splitting into smaller, mature cells.
Liver disease is another frequent cause of high MCV, often (though not always) related to heavy alcohol use. Alcohol itself can raise MCV independently of liver damage by disrupting how red blood cell membranes form. This is why a high MCV sometimes shows up on routine blood work before a person has any symptoms of liver problems. Certain medications, particularly some used in chemotherapy, can also push MCV up by interfering with DNA replication.
What Low MCHC Means
A low MCHC means your red blood cells are paler than normal because they’re carrying less hemoglobin relative to their size. Most microcytic anemias (those with low MCV) are also hypochromic, meaning MCHC drops alongside MCV. Iron deficiency anemia is the classic example: cells become both small and pale. Chronic blood loss and sideroblastic anemia follow the same pattern.
In practice, low MCHC usually shows up alongside low MCV and reinforces the same diagnosis rather than pointing to something entirely different. If your MCV is normal but MCHC is slightly low, it’s less clinically significant and may simply reflect mild variation.
What High MCHC Means
Elevated MCHC is less common than low MCHC and narrows the diagnostic possibilities considerably. The most notable cause is hereditary spherocytosis, a genetic condition where red blood cells lose their normal disc shape and become spheres. Spherical cells have less volume relative to their surface area, which concentrates the hemoglobin inside and raises MCHC. It’s one of the classic laboratory markers for the condition.
Autoimmune hemolytic anemia, where the immune system attacks red blood cells, can also raise MCHC. In both cases, the cells are being destroyed faster than normal, and the abnormal shapes that result tend to pack hemoglobin more densely.
How MCV and MCHC Work Together
Clinicians read MCV and MCHC as a pair to classify anemia into categories, which then guides further testing. The combination creates a practical shorthand:
- Low MCV + low MCHC (microcytic, hypochromic): Points toward iron deficiency, thalassemia, or other hemoglobin production problems. This is the most common anemia pattern worldwide.
- High MCV + normal MCHC (macrocytic, normochromic): Suggests B12 or folate deficiency, liver disease, or alcohol-related changes. The cells are big but hemoglobin concentration stays normal.
- Normal MCV + normal MCHC (normocytic, normochromic): The cells look fine individually, but there aren’t enough of them. This pattern shows up in chronic kidney disease, chronic inflammatory conditions, and early stages of some bone marrow disorders.
No single number on a CBC gives a diagnosis on its own. MCV and MCHC are starting points that tell your provider which direction to investigate. An unexpected result usually leads to follow-up tests: iron studies if the cells are small and pale, B12 and folate levels if they’re large, or a blood smear to look at cell shapes under a microscope if MCHC is elevated.
Why Your Results Might Vary
Normal ranges can shift slightly between laboratories because different machines and calibration methods are used. A result of 79 fL at one lab might be flagged as low while another lab’s range starts at 78 fL. If your result sits right at the edge of the reference range, it’s worth comparing it to your previous blood work rather than reading too much into a single number.
Certain situations can also temporarily affect results. Dehydration concentrates your blood and can nudge MCHC higher. Recent blood loss may not show abnormal MCV right away because it takes weeks for the bone marrow to produce enough new (potentially abnormal) cells to shift the average. If you’ve recently started iron or B12 supplements, your MCV may take two to three months to normalize as your body gradually replaces old red blood cells with properly sized new ones.