MCV and MCHC are two measurements on a standard blood test that describe your red blood cells. MCV (mean corpuscular volume) tells you how big your red blood cells are, while MCHC (mean corpuscular hemoglobin concentration) tells you how packed with hemoglobin they are. Together, they help pinpoint the cause when something is off with your red blood cells, particularly when anemia is suspected.
Both values appear automatically on a complete blood count (CBC), one of the most commonly ordered blood tests. You don’t need to fast for a CBC, and the results typically come back within a day or two.
What MCV Measures
MCV is the average size of your red blood cells, measured in femtoliters (fL). The normal range for adults is roughly 80 to 100 fL. When your red blood cells are smaller than normal (low MCV), the term is microcytic. When they’re larger than normal (high MCV), the term is macrocytic. Cells in the normal range are called normocytic.
This single number narrows down the list of possible causes dramatically. A low MCV points your doctor toward one set of conditions, a high MCV toward a completely different set, and a normal MCV with anemia suggests yet another group of possibilities.
What MCHC Measures
MCHC measures the average concentration of hemoglobin inside each red blood cell, expressed in grams per deciliter (g/dL). The normal value for adults is around 32 to 36 g/dL. Think of it this way: MCV tells you the size of the container, and MCHC tells you how full that container is.
A related value you might see on the same report is MCH (mean corpuscular hemoglobin), which measures the total weight of hemoglobin per cell. MCHC goes a step further by factoring in cell size, giving a concentration rather than just a raw amount. That makes MCHC more useful for spotting certain conditions where cells are the right size but poorly filled with hemoglobin, or unusually dense.
Normal Ranges by Age
Adult reference ranges are fairly stable: 80 to 100 fL for MCV and 31 to 37 g/dL for MCHC. Children, however, have different norms depending on their age. Newborns naturally have much larger red blood cells, with MCV ranging from 95 to 121 fL in the first two days of life. By six months to one year, MCV drops to 70 to 86 fL, which would look abnormally low on an adult scale but is perfectly normal for an infant. By age 18, ranges align with adult values.
MCHC is more consistent across ages, generally falling between 30 and 37 from birth onward. If you’re reviewing a child’s lab results, the age-specific range printed on the report matters more than any general guideline.
What Low MCV Means
A low MCV (below 80 fL in adults) means your red blood cells are smaller than they should be. The most common cause by far is iron deficiency. When your body doesn’t have enough iron, it can’t produce full-sized, hemoglobin-rich red blood cells. A ferritin level below 30 µg/L is the most reliable lab marker confirming iron deficiency as the culprit.
Other causes of small red blood cells include thalassemia (an inherited condition affecting hemoglobin production), chronic disease, lead poisoning, and a rare condition called sideroblastic anemia. A useful clue: thalassemia tends to produce very small cells, often with an MCV below 60 fL, along with a higher-than-normal red blood cell count, while iron deficiency typically shows a lower cell count. Thalassemia also tends to show normal iron levels on lab work, which helps distinguish the two.
Lead poisoning can also shrink red blood cells, and it frequently occurs alongside iron deficiency. A blood smear in lead poisoning classically shows a pattern called basophilic stippling, where tiny dark dots appear inside the red blood cells.
What High MCV Means
A high MCV (above 100 fL) means your red blood cells are larger than normal. The two most common nutritional causes are vitamin B12 deficiency and folate deficiency. Both vitamins are essential for cells to divide properly, and without them, red blood cells grow too large before being released into the bloodstream. Macrocytosis is often the earliest abnormality to show up on a blood count in people with B12 or folate deficiency, sometimes appearing before any symptoms do.
Alcohol use is another frequent cause, and the mechanism is layered. Alcohol can directly enlarge red blood cells, damage the liver (which independently raises MCV), and deplete folate stores. All three effects push MCV higher. Liver disease from other causes, including hepatitis and obstructive jaundice, can raise MCV as well.
Less common causes include hypothyroidism, certain blood cancers like myelodysplastic syndromes, and medications that interfere with DNA synthesis. Some of these can push MCV well above 100 fL, with values over 110 fL more strongly suggesting B12 or folate deficiency or a bone marrow disorder.
What Abnormal MCHC Means
A low MCHC means your red blood cells are paler than normal because they contain less hemoglobin relative to their size. This is called hypochromia. Iron deficiency is the most common cause, and it often appears alongside a low MCV, creating the classic pattern of small, pale red blood cells.
A high MCHC is less common and indicates that red blood cells are unusually dense with hemoglobin. The most well-known cause is hereditary spherocytosis, a genetic condition where red blood cells lose their normal disc shape and become small, rigid spheres. Because these spherocytes have less volume but retain their hemoglobin, the concentration per cell goes up. Severe dehydration and certain other hemolytic conditions (where red blood cells break apart faster than usual) can also raise MCHC.
How MCV and MCHC Work Together
Doctors rarely look at MCV or MCHC in isolation. The combination creates a profile that points toward specific diagnoses:
- Low MCV + low MCHC: Small, pale cells. Classic pattern for iron deficiency anemia and thalassemia.
- High MCV + normal MCHC: Large cells with normal hemoglobin concentration. Typical of B12 deficiency, folate deficiency, or liver disease.
- Normal MCV + normal MCHC with low hemoglobin: Normal-looking cells, just not enough of them. Seen in anemia from chronic kidney disease, chronic inflammation, or acute blood loss.
- Normal MCV + high MCHC: Dense cells. Suggestive of hereditary spherocytosis.
This classification system, called morphologic classification, is the first step in diagnosing anemia. It doesn’t give a final answer on its own, but it tells your doctor which follow-up tests to order, whether that’s iron studies, B12 and folate levels, a blood smear, or something more specialized.
Symptoms That Trigger Testing
You might have a CBC ordered as part of a routine checkup, in which case abnormal MCV or MCHC values could be caught before you notice anything wrong. When symptoms are present, they tend to reflect the underlying anemia rather than the cell size itself. Common signs include fatigue, weakness, shortness of breath, dizziness, headaches, and an irregular heartbeat. These symptoms develop because your blood isn’t carrying enough oxygen to meet your body’s needs, regardless of whether the problem is small cells, large cells, or too few cells overall.
People with chronic conditions like inflammatory bowel disease, celiac disease, heavy menstrual periods, or long-term alcohol use are more likely to develop the nutritional deficiencies that shift MCV and MCHC out of range. In these cases, periodic CBC monitoring can catch changes early, often before symptoms become noticeable.