A blood test showing an unexpected result can cause worry, especially when a term like low Mean Corpuscular Hemoglobin Concentration (MCHC) appears. MCHC is a specific measurement that helps evaluate the health of red blood cells. A low MCHC result means that red blood cells contain less hemoglobin than they should. This finding is a strong indicator of anemia, a condition where the body lacks enough healthy red blood cells to carry adequate oxygen to the tissues.
Understanding MCHC Values and Hypochromia
Mean Corpuscular Hemoglobin Concentration (MCHC) quantifies the average concentration of hemoglobin within a volume of packed red blood cells. Hemoglobin is the protein molecule responsible for binding and transporting oxygen throughout the body. The MCHC value is one of several measurements included in a standard Complete Blood Count (CBC) test.
A low MCHC reading is medically termed hypochromia, meaning the red cells appear paler than normal under a microscope. This paleness occurs because the cells are not sufficiently saturated with hemoglobin. For adults, the typical reference range for MCHC is between 32 and 36 grams per deciliter (g/dL).
MCHC is often evaluated alongside Mean Corpuscular Volume (MCV), which measures the average size of the red blood cells. When both MCHC and MCV are low, it signifies a microcytic, hypochromic anemia, which helps narrow down the possible underlying causes. A significantly low value requires further investigation.
The Primary and Most Common Causes of Low MCHC
The majority of low MCHC cases are attributable to three common conditions that affect the body’s ability to produce functional hemoglobin. Iron deficiency anemia (IDA) is the most frequent cause worldwide. Iron is a foundational component of hemoglobin, and insufficient iron stores directly limit the amount of hemoglobin that can be created.
Chronic blood loss, such as from heavy menstrual cycles or slow bleeding in the gastrointestinal tract, depletes iron stores over time, leading directly to IDA and a drop in MCHC. The body attempts to compensate by producing smaller red blood cells with less hemoglobin, resulting in the microcytic and hypochromic presentation. Addressing the source of blood loss and replenishing iron reserves typically resolves the low MCHC.
Another common cause is thalassemia, an inherited blood disorder affecting hemoglobin production. People with thalassemia trait, a mild form, often have a naturally low MCHC and small red blood cells (microcytosis) without severe health issues. This genetic condition causes the body to produce an altered form of hemoglobin, resulting in the hypochromic appearance even when iron levels are normal.
Anemia of Chronic Disease (ACD), also known as anemia of inflammation, represents a third mechanism resulting in a low MCHC. This occurs in the context of long-term inflammatory conditions, such as autoimmune disorders or chronic infections. The inflammatory response interferes with how the body utilizes stored iron, preventing it from being incorporated into new red blood cells. This functional iron deficiency can lead to a hypochromic picture, even if total body iron stores are adequate.
Addressing the Specific Concern: Low MCHC and Malignancy
While low MCHC prompts further investigation, it is rarely a direct indicator of cancer. The link between low MCHC and malignancy is almost always indirect; the cancer causes a secondary condition that lowers the MCHC value. The most common indirect connection is through chronic, occult blood loss from a tumor, particularly in the gastrointestinal tract, such as in colorectal cancer.
A slow-growing cancer can cause continuous, small amounts of bleeding that go unnoticed. This persistent blood loss eventually leads to severe iron deficiency anemia, characterized by a low MCHC. The low MCHC is a symptom of the iron deficiency, which is a consequence of the tumor. The low MCHC itself does not diagnose cancer, but it serves as a signpost pointing toward the need to investigate the source of the iron loss.
Certain blood cancers, such as leukemia or lymphoma, or their associated treatments, can affect the bone marrow where blood cells are produced. This can lead to a complex anemia that might involve a hypochromic component, though this is less common than the blood loss mechanism. A low MCHC alone is simply a laboratory finding suggesting a deficit in hemoglobin saturation, requiring a complete clinical picture to determine if cancer is the underlying cause.
When to Seek Further Medical Evaluation
A low MCHC result should be discussed with a healthcare provider, as it is a starting point for diagnosis, not the final answer. The next step is typically a blood panel called an iron study to confirm or rule out iron deficiency. This study includes testing for serum ferritin, the most reliable measure of stored iron, and transferrin saturation, which shows how much iron is circulating.
If iron studies are inconclusive or if the patient has a normal iron status, a provider may order a hemoglobin electrophoresis to screen for inherited conditions like thalassemia. If iron deficiency is confirmed, the focus shifts to finding the source of the iron loss. Patients with low MCHC, especially men and postmenopausal women, should be evaluated for gastrointestinal bleeding, often through a fecal occult blood test, endoscopy, or colonoscopy.
The presence of “red flag” symptoms combined with a low MCHC should prompt immediate evaluation. These symptoms include unexplained weight loss, persistent fevers or night sweats, severe fatigue, or visible blood in the stool. The low MCHC is just one piece of data, and professional interpretation is required to integrate it with a patient’s medical history and physical exam to determine the appropriate next steps.