A Complete Blood Count (CBC) is a common laboratory test that provides a detailed look at the cells circulating in your bloodstream, including red cells, white cells, and platelets. Within the red blood cell evaluation is a group of measurements known as the red blood cell indices. These indices help doctors understand the physical characteristics of your red blood cells. One specific and informative measurement on this panel is the Mean Corpuscular Hemoglobin Concentration (MCHC). This value offers insight into the quality of red blood cells and their ability to carry oxygen throughout the body.
Defining Mean Corpuscular Hemoglobin Concentration
Mean Corpuscular Hemoglobin Concentration (MCHC) measures the average concentration, or density, of hemoglobin within a given volume of red blood cells (RBCs). Hemoglobin is the iron-rich protein responsible for transporting oxygen from the lungs to the body’s tissues. The MCHC is calculated by dividing the total hemoglobin measurement by the hematocrit, which is the percentage of your blood volume made up of red blood cells. This measurement is expressed in grams per deciliter (g/dL) or as a percentage. The typical reference range for a healthy adult falls between 32 and 36 g/dL, though this can vary slightly depending on the laboratory performing the test.
What Low MCHC Results Indicate
A result below the normal range is referred to clinically as hypochromia, meaning the red blood cells appear paler than usual when viewed under a microscope. This paleness is a direct reflection of a decreased concentration of hemoglobin inside the cells. A low MCHC suggests red blood cells have a reduced capacity to carry oxygen, often leading to symptoms of anemia like fatigue and weakness. The most frequent cause of low MCHC is iron deficiency anemia. Since iron is required to synthesize hemoglobin, a lack of it causes red blood cell precursors to produce less hemoglobin, resulting in smaller, paler cells with a lower hemoglobin density.
Other Causes of Low MCHC
Low MCHC can also be seen in conditions that impair iron absorption, such as celiac disease or inflammatory bowel disease, or from chronic, low-grade blood loss. Another significant cause of hypochromia is thalassemia, a group of inherited blood disorders where a genetic defect leads to faulty hemoglobin chains. Chronic inflammatory conditions can also cause low MCHC by impairing the body’s ability to utilize the stored iron for hemoglobin production.
What High MCHC Results Indicate
An elevated MCHC is termed hyperchromia, suggesting a higher-than-normal concentration of hemoglobin within the red blood cells. True hyperchromia is biologically uncommon because a red blood cell has a fixed maximum volume and cannot physically hold much more hemoglobin than the normal limit. Therefore, a high MCHC often points to issues with the cell shape or potential measurement artifacts. One primary biological cause is hereditary spherocytosis, a genetic disorder where red blood cells are abnormally spherical. These spherocytes have a reduced surface area to volume ratio, causing the hemoglobin to be artificially concentrated, which registers as a high MCHC.
Artifacts and Other Conditions
Other conditions leading to hyperchromia include severe burns and autoimmune hemolytic anemia, where red blood cells are prematurely destroyed and remnants are measured. In many cases, a high MCHC on an automated blood cell counter is a laboratory error known as an artifact. This occurs when red blood cells clump together, or agglutinate, which the machine interprets as fewer, larger cells with dense hemoglobin content. High MCHC can also be associated with deficiencies in B vitamins, such as folate and B12, which cause the production of abnormally large cells.
Understanding Your Complete Blood Count Results
The MCHC value is only one small part of the larger Complete Blood Count (CBC) panel and must be interpreted alongside other red blood cell indices for an accurate diagnosis. Mean Corpuscular Volume (MCV), which measures the average size of the red blood cells, is frequently used in combination with MCHC. A low MCHC paired with a low MCV (microcytic hypochromic) strongly suggests iron deficiency or thalassemia, while a high MCHC with a normal MCV might point toward hereditary spherocytosis.
Contextualizing the Indices
The Red Cell Distribution Width (RDW), which measures the variation in red blood cell size, also provides essential context. Considering all these indices allows a healthcare provider to effectively classify the type of anemia and determine its underlying cause, as different conditions present with distinct patterns of results. Relying on a single metric like MCHC is insufficient for a full medical assessment. If your MCHC or any other CBC result falls outside the typical range, consulting a healthcare professional is necessary to determine the significance of the findings and decide on appropriate next steps.