Mean corpuscular hemoglobin concentration (MCHC) is a laboratory value found on a complete blood count (CBC) that describes the mean concentration of hemoglobin in a given volume of red blood cells.
Hemoglobin gives red blood cells their color. Consequently, a higher concentration of hemoglobin with a high MCHC makes cells darker (hyperchromic), while a lower concentration with a low MCHC makes them lighter (hypochromic).
The MCHC value is helpful in diagnosing anemia, but is used in conjunction with the red blood cell count and other red blood cell metrics such as mean corpuscular volume (MCV) and red blood cell distribution width (RDW) .
The purpose of the test
Since the MCHC is run as part of the CBC, the test is performed every time the CBC is ordered. For example, this may include routine health exams or during the diagnosis, treatment and follow-up of a wide range of diseases.
Reasons a healthcare provider might Look at MCHC include:
- If you have symptoms of anemia , such as fatigue, pale skin, or dizziness.
- When looking for various causes of anemia (when a person has a low red blood cell count and / or hemoglobin level)
The MCHC is calculated by multiplying the hemoglobin level by 10 and then dividing it by the hematocrit level. The quantity is recorded in grams per liter.
- MCHC = Hb x 10 / hematocrit
The MCHC can also be calculated by dividing the average corpuscular hemoglobin by the average corpuscular volume:
- MCHC = MCH / MCV
Average corpuscular hemoglobin concentration is a measure of the hemoglobin concentration in cells.
Since hemoglobin is a molecule that oxygen binds to, the MCHC is a measure of the average oxygen capacity of red blood cells circulating in the body.
Low MCHC (hypochromia) means a lower concentration of hemoglobin in a given volume of red blood cells and therefore a reduced ability to carry oxygen to the tissues .
Normal (normochromia) or high (hyperchromia) MCHC means that the ability of red blood cells to carry oxygen is normal. However, it may still be insufficient if there are not enough red blood cells present.
There are several limitations that can affect the accuracy of the MCHC reading, including the following.
Since the blood collected after a blood transfusion will be a mixture of donor cells and normal human red cells, the MCHC will not provide accurate information on the original red cells present .
If a person has two different types of anemia that result in different MCHC levels, the readings will not be as helpful in diagnosing the type of anemia. For example, MCHC may be normal if a person has a combination of iron deficiency anemia (which causes a low MCHC) and spherocytosis (which tends to cause a high MCHC) .
Conditions that lead to inaccurate hemoglobin or hematocrit values
Since the MCHC is calculated using the hemoglobin and hematocrit levels, anything that falsely increases or decreases these numbers will give a false MCHC result.
For example, hyperlipidemia (high levels of cholesterol or triglycerides), hyperbilirubinemia (high levels of bilirubin in the blood, as in liver disease), and autoagglutination result in a falsely high hematocrit and a falsely low hemoglobin.
In hemolysis (breakdown of red blood cells), the free hemoglobin in the plasma that remains from the destroyed red blood cells will also cause an abnormal result, that is, the MCHC will be falsely increased .
The average corpuscular hemoglobin (MCH) test measures the average mass of hemoglobin per red blood cell. Although the name is similar to MCHC, it actually provides information more similar to MCV (which affects the amount of hemoglobin in a cell).
Many healthcare providers consider HCM to be the least beneficial of the RBC indices, and in this situation they are looking primarily at MCV. Compared to the average corpuscular hemoglobin, MCHC is a much better test for detecting hypochromia.
- Average corpuscular volume (MCV): MCV is a measure of the average size of red blood cells.
- Red blood cell distribution width (RDW): RDW is a number that reflects the change in the size of red blood cells.
- Average corpuscular hemoglobin (MCH): MCH is the average mass of hemoglobin per red blood cell.
In addition, other tests, such as a peripheral blood smear, may be done to determine the morphology and number of reticulocytes. If indicated, studies of the levels of iron, vitamin B12, and more may be required to further clarify the information found in the general blood test.
Risks and contraindications.
There are very few potential risks with a complete blood count: they include a small risk of bleeding, bruising, or infection.
Before the test
There are no diet or activity restrictions prior to the CBC. It is important to bring your insurance card to your appointment and make sure your healthcare provider has access to the previous CBCs you had to compare.
During the exam
The test can be done in many hospitals and clinics. Before drawing blood, the technician will clean the area (usually a vein in the arm) with an antiseptic and apply a tourniquet to better visualize the vein. If you have a chemotherapy port , blood can be drawn directly from the port.
The technician will then insert the needle into the vein. You may feel a strong jolt as the needle enters and some pressure when the needle remains in place. Some people may feel dizzy or pass out from the needle stick. Be sure to let the technician know if you feel dizzy.
After receiving the sample, the technician will remove the needle and ask you to keep pressure on the site. When the bleeding stops, a bandage or gauze will be placed on it to keep it clean and reduce the chance that it will continue to bleed.
After the test
After the test is over, you can go home and resume your normal activities. Possible side effects include :
- Pain from a needle stick, especially after several attempts.
- Difficulty obtaining a blood sample (for example, in people whose veins are hard to reach due to chemotherapy)
- Bleeding (bleeding may last longer in people taking blood thinners or with a bleeding disorder)
- Large bruise or bruise (may be uncomfortable, but very rare)
- Infection (there is a small risk of bacteria entering the body when the needle is inserted)
interpretation of results
If your clinic has a lab, you may receive the results shortly after the test is complete. In other cases, your healthcare provider may call you with the results. It is important to be your own advocate and ask for real numbers (like your MCHC), not if your CBC is in the normal range.
The "normal" range for MCHC may vary slightly from lab to lab, but is typically 32 to 36. Some labs have a smaller normal range, such as 33.4 to 35.5.
The MCHC is calculated based on hemoglobin and hematocrit, so anything that gets in the way of these numbers will make the MCHC inaccurate. The results will also be inaccurate after the transfusion (they will reflect the characteristics of the transfused cells in combination with the person's own cells).
MCHC can be normal for many types of anemia (normochromic anemias), such as :
- Anemia from blood loss
- Anemia from kidney disease
- Mixed anemias
- Bone marrow failure
- Hemolytic anemias (many types)
Reasons for a low MCHC
When the MCHC is low (unless the result is inaccurate due to one of the limitations noted above), it means that the red blood cells lack hemoglobin. Possible reasons include:
- Iron deficiency (with or without anemia)
- Lead poisoning
- Thalassemias (beta thalassemia, alpha thalassemia, and thalassemia intermedia )
- Sideroblastic anemia
- Chronic disease anemia
A low MCHC without anemia is associated with poor outcomes for people in the intensive care unit. It can also indicate an iron deficiency before anemia develops.
Reasons for a high MCHC
A high MCHC means that the hemoglobin is more concentrated than usual and can occur in a number of ways. For example, hemoglobin becomes more concentrated when red blood cells are destroyed. MCHC is usually elevated in people who smoke. MCHC can also be falsely elevated due to cold agglutinin disease.
Possible causes of a high MCHC in anemia include:
- Autoimmune hemolytic anemia (due to drugs, autoimmune diseases, etc.)
- Hereditary spherocytosis
- Severe burns
- Liver disease
- Sickle cell anemia (homozygous)
- Hemoglobin C disease
Using MCHC with other red blood cell indices
MCHC results are most useful when used in conjunction with other red blood cell counts, especially MCV.
For example, a low MCHC and a low MCV may indicate iron deficiency anemia, thalassemia, sideroblastic anemia, or lead poisoning. A high MCHC and a low MCV may indicate spherocytosis or sickle cell disease.
A normal MCHC and a high MCV can indicate a deficiency of vitamin B12, folic acid, or liver disease .
Other useful tests to classify anemia
In addition to blood and red blood cell counts, additional tests may be required, including the following.
- Peripheral blood smear to determine morphology . With a peripheral blood smear, a sample of blood is examined under a microscope. This allows the lab technician to directly visualize other red blood cell changes that may be associated with anemia, such as target cells, nucleated red blood cells, and more.
- Iron Studies : Serum iron and iron binding capacity and / or ferritin levels can provide valuable information on iron stores and help distinguish iron deficiency from other anemias with low MCHC levels.
- Vitamin B12 Levels : Vitamin B12 levels help treat pernicious anemia.
- Bone marrow aspiration and / or biopsy : In some cases, a bone marrow exam may be necessary to assess the appearance of blood cells in the bone marrow and iron stores.
Get the word of drug information
The MCHC test is more meaningful when combined with other CBC results and may be helpful in determining causes of anemia, as well as in predicting prognosis in patients without anemia. However, when using these results, it is very important to be aware of the limitations and potential for errors, and to use the results only after they have been repeated and supported by other evidence.