MCHC stands for mean corpuscular hemoglobin concentration. It measures how much hemoglobin is packed into each red blood cell relative to the cell’s size. The normal range is 32 to 36 grams per deciliter (g/dL). MCHC isn’t a standalone test; it’s one of several red blood cell measurements automatically calculated as part of a complete blood count, or CBC.
What MCHC Actually Measures
Hemoglobin is the protein inside red blood cells that carries oxygen from your lungs to every tissue in your body. MCHC tells you the concentration of that hemoglobin within a given volume of red blood cells. Think of it this way: if a red blood cell were a glass, MCHC measures how full of hemoglobin that glass is, not just how much hemoglobin is in it overall.
The lab calculates MCHC by dividing your total hemoglobin level by your hematocrit (the percentage of your blood that’s made up of red blood cells), then multiplying by 100. The result is expressed in g/dL. You don’t need to do this math yourself. Automated blood analyzers handle it as part of every CBC.
How MCHC Differs From MCH and MCV
Your CBC report includes several red blood cell “indices” that can look confusingly similar. Each one captures something different:
- MCV (mean corpuscular volume) measures the average size of your red blood cells. Normal is 80 to 100 femtoliters.
- MCH (mean corpuscular hemoglobin) measures the average weight of hemoglobin per red blood cell. Normal is 27 to 31 picograms per cell.
- MCHC measures the average concentration of hemoglobin relative to the cell’s volume. Normal is 32 to 36 g/dL.
MCV and MCH can both be high simply because red blood cells are larger than usual. MCHC corrects for cell size, which is why it’s particularly useful for spotting conditions where red blood cells are either unusually pale (low hemoglobin concentration) or unusually dense (high hemoglobin concentration). In practice, MCV and a related measurement called red cell distribution width (RDW) are used most often to classify anemias, but MCHC adds a specific layer of information that other indices don’t.
What Low MCHC Means
A low MCHC, generally below 32 g/dL, means your red blood cells contain less hemoglobin than expected for their size. Under a microscope, these cells look paler than normal, which is why the medical term for this is “hypochromic.” The most common cause is iron deficiency. Without enough iron, your body can’t produce adequate hemoglobin, so each red blood cell ends up diluted.
Other conditions that can lower MCHC include thalassemia (an inherited condition that reduces hemoglobin production), chronic blood loss from heavy periods or gastrointestinal bleeding, and certain rare genetic disorders that impair iron transport within cells. In some of these conditions, the body actually has plenty of iron in the bloodstream but can’t move it into developing red blood cells, resulting in pale, small cells despite normal or even elevated iron stores.
Low MCHC often appears alongside a low MCV, meaning the red blood cells are both small and pale. This combination is a classic pattern that helps narrow down the likely cause.
What High MCHC Means
A high MCHC, above 36 g/dL, is less common and points to a narrower set of possibilities. It means hemoglobin is packed more densely than usual into the red blood cells.
The condition most strongly associated with elevated MCHC is hereditary spherocytosis, an inherited disorder where red blood cells lose their normal disc shape and become small, rigid spheres. Because the cells shrink while retaining the same amount of hemoglobin, the concentration goes up. Autoimmune hemolytic anemia, where the immune system attacks red blood cells, can also produce spherical cells and raise MCHC. Sickle cell disease and hemoglobin C disease (another inherited hemoglobin variant) are additional causes.
Severe burns can elevate MCHC through a different mechanism. Metabolic changes after major burns can make red blood cells stiff and dehydrated, concentrating the hemoglobin inside them and making them vulnerable to breaking apart in small blood vessels.
False Elevations to Be Aware Of
High MCHC results sometimes reflect a lab artifact rather than a real problem in your blood. Lipemia (high fat levels in the blood sample, often from eating before the draw) falsely inflates the hemoglobin reading, which pushes the calculated MCHC up. The same thing happens if the blood sample breaks down before analysis, a problem called in vitro hemolysis. Red blood cell clumping, which can occur with certain immune conditions or even cold temperatures affecting the sample, also produces falsely high results. If your MCHC comes back elevated without a clear clinical explanation, your doctor may repeat the test or check for these interfering factors.
How the Test Works for You
Because MCHC is part of a standard CBC, there’s nothing special you need to do to prepare. No fasting is required unless your doctor has ordered other blood tests at the same time that call for it. The blood draw itself is a routine arm stick, and results typically come back within a day or two.
MCHC is rarely interpreted on its own. Your doctor will look at it alongside MCV, MCH, hemoglobin, hematocrit, and other CBC values to build a complete picture of your red blood cell health. A single slightly out-of-range result doesn’t necessarily indicate disease. But a significantly abnormal MCHC, especially combined with symptoms like fatigue, shortness of breath, or pale skin, often prompts further investigation such as iron studies, a blood smear viewed under a microscope, or additional tests targeting specific conditions like thalassemia or spherocytosis.