A routine blood test, known as a Complete Blood Count (CBC), provides a detailed snapshot of the cells circulating in the bloodstream. One specific metric reported is the Mean Corpuscular Hemoglobin Concentration, or MCHC. An elevated MCHC indicates an unusual characteristic of the red blood cells and signals a need for further investigation. This value alone does not constitute a diagnosis but points toward underlying conditions affecting red cell structure.
Understanding the MCHC Value
The MCHC is a calculated value quantifying the average concentration of hemoglobin within a fixed volume of packed red blood cells. Hemoglobin is the protein responsible for transporting oxygen, making MCHC a measure of red cell density. The value is obtained by dividing the total measured hemoglobin by the hematocrit (the percentage of blood volume occupied by red blood cells).
The typical reference range for MCHC is 32 to 36 grams per deciliter (g/dL). A result above this range is an elevated MCHC, or hyperchromia. This suggests the red cells are highly saturated with hemoglobin for their size, often indicating a smaller, denser cell.
Conditions That Cause High MCHC
An elevated MCHC can arise from a genuine change in the red blood cells or an artificial reading caused by laboratory interference. The most common biological cause involves conditions that lead to the formation of spherocytes—small, dense, sphere-shaped red cells. These cells lose a portion of their membrane but retain their hemoglobin, resulting in a high concentration reading.
Biological Causes
Hereditary Spherocytosis is a genetic disorder where defects in red cell membrane proteins cause the cells to become fragile and spherical. This is the classic cause of an elevated MCHC. Autoimmune Hemolytic Anemia (AIHA) is another significant cause, where the immune system produces antibodies that damage red blood cells. This process causes the cells to lose membrane and become spherocytic before premature destruction.
Severe burns can cause rapid, non-immune red cell damage, leading to fragmentation and subsequent hemoglobin concentration within the remaining cells. High MCHC is also seen in certain hemoglobinopathies, such as Hemoglobin C disease, which causes denser cells. In severe B12 or folate deficiency, the MCHC calculation may sometimes lead to a high reading alongside other abnormal blood indices.
Artifactual Causes
The most frequent reason for a very high MCHC (over 37 g/dL) is a measurement artifact in the laboratory, not a true biological change. The presence of cold agglutinins, antibodies that cause red cells to clump together at lower temperatures, is a prime example. When automated analyzers measure these clumps, the machine incorrectly counts a low number of large cells and calculates a falsely elevated MCHC. Similarly, severe lipemia (high levels of fat particles in the blood) can interfere with the photometric measurement of hemoglobin, causing a falsely high result.
Diagnostic Follow-Up and Evaluation
When an elevated MCHC is reported, the initial step is determining if the result is biological or spurious. If cold agglutinins are suspected, the laboratory can warm the sample to 37 degrees Celsius to break up cell clumps and re-run the test, confirming the artifact. If the MCHC remains elevated after ruling out interference, the focus shifts to investigating the patient’s clinical picture.
Other CBC indices are reviewed, particularly the Mean Corpuscular Volume (MCV) and the Red Cell Distribution Width (RDW). An elevated MCHC combined with a low MCV suggests spherocytosis. A peripheral blood smear involves manually examining the blood under a microscope to visually identify spherocytes or red cell clumping.
If red cell destruction (a hemolytic process) is suspected, specialized tests are ordered. The Direct Antiglobulin Test (Coombs test) detects antibodies attached to red blood cells, confirming Autoimmune Hemolytic Anemia. If Hereditary Spherocytosis is suspected, an Osmotic Fragility Test assesses the red blood cell membrane’s ability to withstand swelling in hypotonic solutions.
Treatment Strategies for Elevated MCHC
The MCHC is a marker, not the disease itself; therefore, treatment must target the underlying cause of the red cell abnormality. If the elevation was spurious due to cold agglutinins, the issue is resolved by warming the sample or by the patient avoiding cold exposure. No direct medical treatment is required for the MCHC value in these artifactual situations.
If Autoimmune Hemolytic Anemia is confirmed, standard initial treatment involves immunosuppressive medications, such as corticosteroids, to reduce the immune system’s attack on red cells. For severe or non-responsive cases, other immunosuppressants or a splenectomy (surgical removal of the spleen) may be considered to reduce the site of red cell destruction.
For Hereditary Spherocytosis, management ranges from close monitoring for mild cases to intervention for severe disease. Patients are often prescribed folic acid supplementation to support red blood cell production. Splenectomy is a potential intervention for individuals with severe, chronic hemolysis to alleviate anemia and reduce the need for blood transfusions.