MCH, MCHC, and MCV: Diagnostic Significance and Clinical Insights
Authors: Payal Bhandari M.D., Nigella Umali Ruguian
Contributors: Tejal, Vivi Chador, Hailey Chin
Key Insights
The Complete Blood Count (CBC) tests red blood cells (RBC), white blood cells (WBC), platelets, and other blood factors. RBCs make up 45% of blood in adults and 60% in newborns. They carry oxygen through the body with a protein called hemoglobin (Hb). The Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), and Mean Corpuscular Volume (MCV) tests measure RBC size and oxygen-carrying ability, important for cell energy. These tests help diagnose conditions like anemia (low RBC/Hb) or polycythemia (high RBC/Hb) and provide insight into overall health and treatment needs.
Figure 1: After blood is processed, it separates into three layers: 55% plasma (mostly water), 45% red blood cells, and 1% white blood cells (WBCs) and platelets. WBCs fight infections, and platelets help heal wounds by forming clots and supporting new blood vessels.
What are the Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Concentration (MCHC), and Mean Corpuscular Volume (MCV) Tests?
MCH Test
The mean corpuscular hemoglobin (MCH) test measures the average mass of hemoglobin (Hb) per red blood cell (RBC). MCH is calculated by dividing the total mass of Hb by the number of RBCs in a blood sample16.
MCH= Hemoglobin in g/1000ml of bloodRBC count in millions/mlpg/cell
Figure 2: The central pallor is the light area in a red blood cell (RBC) that holds hemoglobin (Hb). Normochromic RBCs have normal Hb levels. Hyperchromic means less Hb, and hypochromic means more. The mean corpuscular hemoglobin (MCH) decreases when Hb goes down and increases when Hb goes up.
MCHC Test
The mean corpuscular hemoglobin concentration (MCHC) test calculates the average Hb concentration in a single RBC. It is derived by dividing Hb by the hematocrit (ratio of packed RBCs comprising a unit volume of blood). MCHC is expressed as grams per deciliter (g/dl) of RBCs or as a percentage value. The normal values for MCHC are 34 ± 2 g/dl16.
MCHC= (Hemoglobin in g/100ml of blood )100Volume of packed cells/100ml of blood g/dl or %
MCHC is unaffected by Hb production but is affected by the size and volume of the RBC concentration in the blood. On the other hand, MCH is unaffected by the RBC count but impacted by Hb production.
Figure 3: The figure shows that when MCH is high, MCHC is also high, and when MCH is low, MCHC is low. MCHC measures how much hemoglobin is in each red blood cell. High MCHC means the cells have more hemoglobin, while low MCHC means they have less. MCH, or hemoglobin weight per cell, increases with MCHC and decreases with lower MCHC.
MCV Test
The mean corpuscular volume (MCV) test measures the red blood cell (RBC) size and is expressed as femtoliters (10−15; fl) or cubic microns (μm3). The normal values for MCV are 87 ± 7 fl.
MCV = Volume of packed cells/1000ml of bloodRBC count in millions/ml fl or m3
The MCV is a critical measurement to identify RBCs’ oxygen-delivery capacity. The MCV gradually increases with age, following two linear subsets—patients aged 1 to 25 and 26 to 88. In the demographic of individuals aged 40 to 80, females typically display lower MCV values compared to males.
Figure 4: Red blood cells (RBCs) can be too small (microcytic) or too large (macrocytic). In both cases, hemoglobin can’t carry oxygen properly, reducing oxygen in tissues and affecting organ function.
Hemoglobin Formation
Hemoglobin (Hb) is a protein in red blood cells that gives blood its red color and makes up 96-97% of their dry weight. It is mostly made in the bone marrow, with a small amount made in the liver. Globins are proteins in the blood that help transport molecules and support the immune system. Vitamin B12, B9 (folate), and iron help hemoglobin carry oxygen. The stomach controls vitamin B9 and B12, while iron is absorbed in the small intestine.
Figure 5: Hemoglobin (Hb) has four sites for oxygen. It’s made of four subunits, each with a heme group attached to two alpha chains and two other chains. The structure is held together by sugar and disulfide bonds. An iron atom at the center of each hemoglobin binds oxygen with help from vitamins B12 and B9.
Figure 6: Hemoglobin (Hb) is made in red blood cells (RBCs) by combining heme groups and globin proteins. The iron in heme (Fe2+) binds to oxygen, changing blood color from dark purple (venous) to bright red (arterial). When exposed to certain chemicals, the iron turns into Fe3+ (methemoglobin), which can’t carry oxygen.
Red Blood Cell Formation
All blood cells come from hematopoietic stem cells, also called hemocytoblasts. These cells can develop into myeloid progenitor cells. Inside the bone marrow, which is found mainly in flat bones like the skull, ribs, pelvis, and sternum, hemocytoblasts turn into immature red blood cells (reticulocytes), platelets, and white blood cells (leukocytes). About 60-70% of these stem cells become white blood cells.
Figure 7: Blood cells start from hematopoietic stem cells, also called hemocytoblasts. These cells turn into myeloid progenitor cells in the bone marrow, found in flat bones like the skull, ribs, pelvis, and sternum. The marrow makes red blood cells, platelets, and white blood cells (WBCs), which later become monocytes, lymphocytes, eosinophils, neutrophils, and basophils.
Reticulocytes are young red blood cells (RBCs) that are slightly larger and still contain ribosomal RNA. Mature RBCs have no nucleus or mitochondria, which helps them carry oxygen. Without mitochondria, RBCs use glucose for energy. RBCs live for about 120 days, then are broken down in the bone marrow, spleen, or liver. Low oxygen levels in the blood cause the kidneys to release erythropoietin (EPO), which helps make new RBCs in about seven days.
Figure 8: The Life Cycle of Red Blood Cells (RBCs; Erythrocytes) . Low blood oxygen causes red blood cells (RBCs) to break down faster. The kidneys release erythropoietin (EPO), and the thyroid makes hormones to boost RBC production. Nutrients like iron, zinc, and vitamins from food help make RBCs in about seven days. When RBCs lose energy, they’re broken down by cells in the liver, spleen, and bone marrow. Hemoglobin and iron are recycled or removed from the body. Heme turns into bilirubin, which is stored as bile or excreted. Iron is stored or carried to the bone marrow to make new RBCs. Globin is sent to the liver to make amino acids.
Role of Hemoglobin and Red Blood Cells in the Body
Red blood cells (RBCs) carry oxygen (O2) from the lungs to the body’s tissues and remove carbon dioxide (CO2) when we exhale. RBCs also help maintain the blood’s acidity (pH), which is essential for cells to work properly. Think of RBCs as a car, with hemoglobin (Hb) as the driver. Hemoglobin picks up O2 in the lungs and delivers it to the body through tiny blood vessels.
Figure 9: Red blood cells (RBCs) primary job is to carry oxygen (O2) to tissue and release the waste product, carbon dioxide (CO2), during exhalation. RBCs contain around 640 million hemoglobin molecules per cell.
Figure 10: 98 to 99 percent of O2 is transported to cells by binding to hemoglobin in red blood cells, then travels through the alveoli in the lungs and is transported to tissue throughout the body. Due to oxygen’s low solubility, less than 2 percent of the total O2 delivered in arterial blood is dissolved in blood plasma.
Regulation of MCH, MCHC, and MCV Blood Levels
MCH, MCHC, and MCV blood levels are linked to the liver’s ability to make proteins for hemoglobin (Hb) and red blood cells (RBCs). This process depends on the body’s energy levels and its ability to control reactive oxygen species (ROS).
Cells use oxygen, hydrogen (from water), and carbon (from food) for energy. In low energy states, like fasting or intense exercise, the body breaks down fat and muscle. The brain can’t use fat directly, so it turns fat into glucose through ketogenesis, helping stabilize blood sugar, fat stores, appetite, mood, and hormones.
Figure 11: Cellular respiration is a process where the body turns energy from plants and microorganisms into high-energy molecules like ATP, NADH, and FADH. This process also releases CO2 when we exhale. It happens in three steps, with the most energy being made in the electron transport chain in the cell’s mitochondria, producing 34 ATP, plus 2 ATP from glycolysis and the Krebs cycle.
Reduced ketogenesis causes too much glucose in the blood, which binds to hemoglobin (Hb) and thyroglobulin in the thyroid, leading to:
Less oxygen: Hb can’t carry oxygen well, reducing oxygen to tissues and affecting organ function.
Thyroid hormone release: Glycation of thyroglobulin releases thyroid hormones (TH), which break down glucose, fat, and protein. TH also regulates metabolism, energy, body temperature, and organ functions.
Low oxygen: The kidneys make erythropoietin (EPO), which increases red blood cell and hemoglobin production.
Energy imbalance: Too much glucose, protein, and fat disrupt hormone balance, causing reactive oxygen species (ROS) that damage cells, lead to inflammation, and trigger atherosclerosis, which harms red blood cells and may increase their production.
Figure 12: Fat cells, liver, and muscles break down fats, amino acids, and other substances to make glucose and ketones. Ketones provide energy during fasting, intense exercise, or low insulin. They offer much more energy than glucose. This process is influenced by the body’s sleep-wake cycle.
Clinical Significance of Low MCH, MCHC, and MCV Blood Levels
Microcytic anemia occurs when blood markers—MCH, MCHC, and MCV—are low.
Low MCH means less hemoglobin in each red blood cell (RBC). Low MCHC means less hemoglobin in the RBCs, and low MCV means the RBCs are smaller. This reduces oxygen in the blood and makes it harder for tissues to get oxygen. RBCs also struggle to remove carbon dioxide.
Low oxygen levels (hypoxia) can damage cells, and the body focuses on stopping bleeding and healing. RBC production increases temporarily but their lifespan shortens. If more RBCs are made, MCH and MCHC can drop even if hemoglobin stays the same.
Dehydration often causes low MCH, MCHC, and MCV levels. Since blood is mostly water, dehydration thickens it, making it harder for oxygen to bind to hemoglobin (Hb). Dehydration shrinks cells, affecting their function. Short-term dehydration boosts RBC and Hb production but makes RBCs smaller, raising MCH and MCHC and lowering MCV. Long-term dehydration reduces RBC lifespan and Hb production, leading to lower MCH, MCHC, and MCV. It also affects digestion, causing nutrient deficiencies (iron, B6, B9, B12) that impact RBC and Hb production.
Figure 13: Osmosis is the movement of water in and out of cells based on solute concentration. In hypotonic cells, more water enters because there’s a higher solute concentration inside. In isotonic cells, water moves in and out equally. In hypertonic cells, water leaves because there’s less solute inside.
Dehydration can be caused by:
Burns
Diarrhea
Overusing diuretics or laxatives
Sweating from exercise or heat stroke
Not drinking enough water
Not enough breast milk in newborns
Excess blood loss (e.g., heavy periods, chronic illness, surgery, or frequent blood donation)
Dehydration thickens the blood, raises blood pressure, and makes it harder for the lungs to get oxygen and remove carbon dioxide. This leads to cell damage, gene mutations, and slower cell growth. Inflammation occurs, which can cause tissue damage, blood clots, and narrowed blood vessels. Over time, this damages organs like the bone marrow, kidneys, and thyroid, lowering red blood cell production. This shows up as low MCV, MCH, and MCHC levels.
Figure 14: Atherosclerosis is when arteries become thick and stiff from fat, plaque, and scar tissue. This can cause blood clots and block blood flow, raising blood pressure. It can damage organs and lead to heart disease, circulation problems, and aneurysms.
Clinical Significance of High MCH, MCHC, and MCV Blood Levels
Macrocytic anemia means red blood cells (RBCs) are larger than normal (high MCV) compared to hemoglobin (Hb). There are two types:
Hyperchromic non-megaloblastic anemia: Both MCH and MCV are high, but MCHC is normal. It’s usually caused by liver or thyroid issues that affect red blood cell and hemoglobin production.
Megaloblastic anemia: MCHC and MCV are high, but MCH is normal. It’s caused by a lack of vitamin B12 or folate, which leads to DNA damage in immature RBCs, preventing them from maturing.
Vitamin B12 and folate tests help determine the type and cause of macrocytic anemia.
Figure 15 shows how vitamin B12 and folate levels affect macrocytic anemia. Low vitamin B12 with normal folate can be caused by stomach or small intestine issues, which reduce nutrient absorption and energy. Low levels of both B12 and folate are often due to small bowel diseases. The diagram shows how these levels help find the cause and treatment for macrocytic anemia.
The most common cause of high MCH, MCHC, and MCV blood levels is reduced concentration and abundance of healthy gut bacteria (dysbiosis).
Figure 16: A healthy gut microbiota helps with digestion, nutrient absorption, and waste removal. When it’s imbalanced (dysbiosis), it slows fat metabolism, increases harmful ROS, and damages cells. This can lower energy, change metabolism, and harm the liver, leading to lower red blood cell production and anemia.
Chronic dysbiosis and dehydration cause nutrient deficiencies, like B12, B9, iron, and zinc. These deficiencies affect hemoglobin, reducing oxygen delivery to tissues and shortening red blood cell (RBC) lifespan. The liver works harder to clear byproducts from old RBCs, using up energy needed by other organs, like the digestive system. This worsens digestion, increases nutrient deficiencies, and impacts body functions.
Macrocytic anemia is linked to increased white blood cells, platelets, and smooth muscle cells, which help repair tissue. This causes atherosclerosis, where excess RBCs lead to clotting, fat buildup, and narrow blood vessels, reducing blood flow. Thick blood and poor circulation damage organs like the liver and pancreas, leading to problems like diabetes, hormone imbalances, vascular diseases, and cancer. High MCH, MCHC, and MCV levels raise the risk of organ damage.
Conclusion
The MCH, MCHC, and MCV tests help diagnose blood conditions. Low levels usually mean anemia, where there aren’t enough red blood cells (RBCs) to carry oxygen. High MCH and MCHC levels suggest polycythemia, where RBCs carry too much oxygen. Both can be caused by dehydration, nutrient shortages, or gut problems, leading to inflammation and tissue damage.
These issues raise the risk of serious health problems, like heart disease, cancer, and organ failure. Fixing abnormal levels involves improving diet, sleep, stress, and gut health, with a focus on hydration, medication, and reducing toxins.
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