A low value for Mean Corpuscular Hemoglobin Concentration (MCHC) on a routine blood test can be a source of concern. The MCHC is a calculated value that measures the average concentration of hemoglobin within your red blood cells, which transport oxygen throughout the body. A low MCHC indicates that the red cells contain a reduced amount of this oxygen-carrying protein. While this finding is common and often points to a readily treatable condition, it warrants discussion with a healthcare provider to determine the underlying cause.
Understanding MCHC in a CBC Panel
The MCHC is one of several measurements included in a Complete Blood Count (CBC) test. This value is calculated by dividing the total amount of hemoglobin by the volume of packed red blood cells, giving a concentration measurement. The typical reference range for MCHC is approximately 32 to 36 g/dL, and a result below this range is referred to as hypochromia.
This index is informative when considered alongside Mean Corpuscular Volume (MCV), which measures the average size of the red blood cells. A low MCHC combined with a low MCV suggests a microcytic, hypochromic anemia, where red blood cells are both smaller and paler due to the low hemoglobin concentration.
Primary Conditions Causing Low MCHC
The most frequent reason for a low MCHC result is Iron Deficiency Anemia (IDA), caused by a lack of sufficient iron to manufacture adequate hemoglobin. Iron is a fundamental component of the hemoglobin molecule, so a shortage directly impairs the red blood cells’ ability to become fully saturated. This deficiency often results in the production of red blood cells that are smaller and paler.
Iron depletion can stem from several factors, including insufficient dietary iron intake, poor absorption (like due to celiac disease), or chronic, low-grade blood loss. Common scenarios for chronic blood loss leading to IDA include heavy menstrual periods or gastrointestinal bleeding from ulcers or certain cancers.
Low MCHC can also be a feature of Thalassemia, an inherited group of blood disorders that interfere with the production of the globin chains that form hemoglobin. In Thalassemia, the genetic defect causes the red blood cells to be small and have a reduced hemoglobin concentration.
Another possibility is Anemia of Chronic Disease, which can sometimes present with a low MCHC. This type of anemia is related to chronic inflammatory states, where the inflammatory process interferes with the body’s ability to properly utilize stored iron. Other, less common causes include lead poisoning or a deficiency in Vitamin B6, both of which can impair the synthesis of hemoglobin.
Symptoms That May Accompany Low MCHC
The underlying lack of oxygen-carrying capacity often leads to recognizable symptoms. The most common complaint is persistent fatigue and generalized weakness, which stem from tissues and organs not receiving enough oxygen. This lack of oxygen delivery can also manifest as shortness of breath, particularly during physical exertion.
Physical signs can include pallor, or pale skin and gums, due to the reduced concentration of hemoglobin in the blood.
In more pronounced cases, the body’s compensatory mechanisms may lead to symptoms like a rapid or irregular heartbeat, as the heart works harder to circulate the limited oxygen supply. Symptoms tend to become more noticeable and severe as the MCHC level drops further and the underlying condition progresses.
Diagnostic Steps and Treatment Options
When a low MCHC is detected on a CBC, the immediate next step is to perform additional blood tests to pinpoint the precise cause, as the MCHC itself is a screening indicator, not a definitive diagnosis. The primary follow-up tests are often iron studies, which include measuring serum ferritin to assess the body’s iron stores. A low ferritin level is a strong indicator of iron deficiency, confirming IDA as the cause of the low MCHC.
If iron levels are normal despite the low MCHC, a healthcare provider may order a hemoglobin electrophoresis test to screen for Thalassemia or other genetic hemoglobin disorders. Once the root cause is established, treatment can be initiated, with the most common approach for IDA being oral iron supplementation. These supplements, often taken with dietary modifications to increase iron-rich foods, aim to replenish the body’s iron stores and restore normal hemoglobin production.
Treatment for other causes is different; for example, Thalassemia management ranges from simple monitoring in mild cases to regular blood transfusions in severe forms. It is important to remember that iron supplementation is inappropriate and potentially harmful for anemias not caused by iron deficiency, such as Thalassemia, underscoring the necessity of a proper diagnosis. Regular monitoring of blood indices is required throughout treatment to ensure the levels are returning to the normal range and that the underlying issue has been successfully addressed.