Guide to Mean Corpuscular Hemoglobin (MCH)

WRITTEN BY

The Levels Team

Updated: 05/22/2025|12 min read

Summary

Mean corpuscular hemoglobin (MCH) is a measurement of the average amount of hemoglobin contained in each of your red blood cells. 

Why It Matters

Hemoglobin is the iron-containing protein that allows red blood cells to carry oxygen from your lungs to tissues throughout your body. MCH (Mean Corpuscular Hemoglobin), measured in picograms (pg) per cell, tells you the average weight of hemoglobin in each red blood cell.

MCH differs from related measurements in specific ways:

• MCH vs. MCHC: MCH measures the average amount of hemoglobin per cell, while MCHC measures how densely that hemoglobin is packed within the cell volume.
• MCH vs. MCV: While MCV measures average red blood cell size, MCH measures their hemoglobin content. These typically change together but can sometimes vary independently.
• MCH vs. Hemoglobin: Total hemoglobin measures overall oxygen-carrying capacity, while MCH focuses on individual cell content, helping identify cellular issues even when total hemoglobin appears normal.

When MCH is low (hypochromia), red blood cells contain less hemoglobin than normal, potentially reducing oxygen delivery to tissues despite normal red blood cell counts. High MCH (hyperchromia) typically occurs with larger-than-normal red blood cells, as seen in conditions like vitamin B12 or folate deficiency.

MCH helps categorize different types of anemias and blood disorders, providing critical information about red blood cell function when interpreted alongside other measurements.

Associated Symptoms

Low MCH (hypochromia) symptoms typically relate to the underlying condition causing the abnormality or to reduced oxygen delivery if hemoglobin is significantly affected. These symptoms can include:

• Fatigue and weakness, especially during physical activity
• Pale skin, nail beds, and mucous membranes
• Shortness of breath with exertion
• Dizziness or lightheadedness
• Cold hands and feet
• Brittle nails or spoon-shaped nails (koilonychia) in iron deficiency

High MCH symptoms are also often related to the underlying condition and can include:

• Shortness of breath
• Chest pain
• Fatigue
• Pale skin
• Numbness or tingling in hands and feet
• Balance problems
• Cognitive changes or memory issues

Clinical Ranges

Lab Reference Range: 26.60-33.00 pg

Lifestyle Factors That Can Impact It

Factors that may increase MCH include the following:

• Iron supplementation if previously deficient 
• Vitamin B12 and folate-rich diet or supplements 
• Adequate protein intake 
• Vitamin C consumption with iron-containing foods 

Factors that may decrease MCH include the following:

• High consumption of foods that inhibit iron absorption (tea, coffee, high-calcium foods with meals)
• Vegetarian or vegan diet without proper supplementation
• Excessive endurance exercise ("sports anemia")
• Blood donation (frequent donations without adequate iron repletion)
• Significant alcohol consumption 

Other Factors That Can Impact It

Medical Conditions

• Iron deficiency: Decreases MCH as less hemoglobin is produced due to insufficient iron, the essential building block for hemoglobin
• Thalassemia traits and diseases: Lower MCH through inherited defects in hemoglobin production despite normal iron levels
• Chronic kidney disease: Often decreases MCH due to reduced erythropoietin production, which stimulates red blood cell production
• Vitamin B12 or folate deficiency: Typically increases MCH because red blood cells grow larger but division is impaired, resulting in fewer but larger cells
• Liver disease: Can increase MCH through accumulation of lipids in red cell membranes, impaired cell maturation, and too much hemolysis; can also decrease MCH
• Alcoholism: Raises MCH due to direct toxic effects on bone marrow and interference with B-vitamin metabolism

Medications

• Chemotherapy drugs: Can decrease MCH through suppression of bone marrow activity and hemoglobin synthesis; can also increase levels
• Certain antibiotics (chloramphenicol, trimethoprim): Can increase MCH
• Anticonvulsants such as phenytoin: Can lower MCH through interference with folate metabolism
• Oral contraceptives: May increase MCH slightly by affecting iron retention
• Antiretroviral medications: Can increase MCH

Testing Accuracy and Stability

MCH testing is generally reliable, but a few rare factors can influence your results.

Factors That Can Affect the Accuracy of Your Test

• Recent blood transfusions can alter MCH results for 1--3 months, reflecting donor blood characteristics rather than your own.
• Very high white blood cell counts can artificially increase measured hemoglobin without affecting red cell count, falsely raising MCH.
• Lipemia (excess lipids in blood) can interfere with hemoglobin measurement, potentially causing falsely elevated results.

How it Relates to Other Markers

MCH is most meaningful when interpreted alongside other red blood cell and nutritional measurements, including:

• Mean corpuscular volume (MCV): MCV measures the average size of your red blood cells. Cell size and MCH usually change together---small cells (low MCV) typically contain less hemoglobin (low MCH), while large cells (high MCV) often contain more hemoglobin (high MCH).
• Mean corpuscular hemoglobin concentration (MCHC): Tells you how concentrated the hemoglobin is within the red blood cell. If MCH is low but MCHC is normal, it may suggest the cells are small but have normal hemoglobin concentration.
• Red cell distribution width (RDW): Indicates how uniform your red blood cells are in size. Elevated RDW with abnormal MCH may suggest a developing or mixed nutritional deficiency.
• Hemoglobin and hematocrit: These are overall measures of your blood's oxygen-carrying capacity. MCH helps explain why these values might be abnormal.
• Iron studies: Ferritin, iron, and total iron binding capacity help determine if low MCH is due to iron deficiency or another cause.
• Vitamin B12 and folate levels: These tests help determine if high MCH is related to these deficiencies.

What Results May Mean in the Context of Other Markers

• Low MCH with low MCV (microcytic, hypochromic): May suggest iron deficiency or thalassemia trait; cells are small and pale.
• High MCH with high MCV (macrocytic, hyperchromic): May suggest vitamin B12 or folate deficiency, certain medications, or liver disease; cells are large with more hemoglobin.
• Normal MCH with normal MCV (normocytic, normochromic): May reflect a healthy pattern or may be seen in anemia of chronic disease.
• Low MCH with normal MCV (normocytic, hypochromic): May indicate early iron deficiency or a combination of iron deficiency with another condition that increases MCV.
• Abnormal MCH with abnormal white blood cell or platelet counts: May indicate bone marrow disorders affecting multiple cell lines.

Follow-up Considerations

If your MCH value is abnormal, your health care provider will consider this with your other markers from your CBC and develop a personalized approach that may include addressing underlying nutritional deficiencies, treating chronic conditions, or additional testing to determine the cause. This may include retesting to monitor response to interventions. You should always speak to your doctor if you have medical questions or before making medical decisions.

Additional Testing or Monitoring Your Doctor May Consider

• Reticulocyte count
• Hemoglobin electrophoresis (for suspected thalassemia)
• Kidney function tests
• Liver function tests
• Lead levels (particularly in children with unexplained low MCH)
• Inflammatory markers, such as C-reactive protein (if anemia of chronic disease suspected)
• Bone marrow examination (in severe or unexplained cases)

When Additional Care May be Warranted

• Abnormal MCH with symptoms of anemia
• Abnormal MCH with multiple abnormal cell lines
• Persistent abnormalities despite appropriate treatment
• MCH abnormalities in pregnancy
• Progressive decline in MCH over multiple measurements
• New-onset abnormalities in those over 60 (to rule out myelodysplastic syndromes)

Bibliography