What is a MCH Blood Test
Why is a MCH Blood test needed?
An MCH blood test can be used to determine the presence of disorders like those mentioned below.
Hemoglobin is an iron-rich protein used to transport oxygen throughout the blood stream. It is found in heavy concentrations in the red blood cells of all vertebrate animals. It serves to assist the red blood cells in the transport of oxygen from the respiratory organs (such as gills or lungs) to other tissues located throughout the body. Hemoglobin allows the red blood cell to release oxygen into other tissues, which facilitates burning nutrients to create energy so that the organism can live. It also allows the red blood cell to channel carbon dioxide – a byproduct of cellular processes when oxygen is used – back to the respiratory organs, where the carbon dioxide will be released into the environment through the process of breathing. In all mammals, red blood cells are mostly composed of hemoglobin and water. Each molecule of hemoglobin found in a mammalian cell can carry up to four molecules of oxygen each. Variants of hemoglobin exist, even within an individual species, though one is usually more common that others. These variations are the result of genetic mutations, and many of them do not cause any disease or noticeable affect in terms of quality of life. However, some mutant forms of hemoglobin may cause a range of hereditary diseases known as hemoglobinopathies. The most well-known sort of hemoglobinopathic disease is sickle-cell anemia or sickle-cell disease, which was the first human disease that was understood at a molecular level. This sort of disease is most common among patients with ethnic heritages linked to Africa, the Mediterranean basin, and Southeast Asia. Around 7 percent of the world’s population is suspected to carry a gene that causes this sort of disorder. Additionally, some persons suffer from a different sort of inherited blood disorder affecting hemoglobin thalassemia, where a gene mutation or deletion results either in the underproduction of hemoglobin, or production of faulty hemoglobin molecules. Both hemoglobinopathies and thalassemias are suspected to be associated with evolutionary responses to the prevalence of malaria in certain regions. This is because the possession of one or more genes causing the conditions can increase natural resistance to the malaria infection, whereby parasites invade the body’s red blood cells.
The MCH blood test, along with the MCV (Mean Corpuscular Volume) and MCHC (Mean Corpuscular Hemoglobin Concentration) tests, can be used to determine the presence of disorders like those mentioned above. MCH tests are specifically used to detect an iron deficiency or overproduction of hemoglobin. Either can cause a variety of medical issues.
MCH and Hemoglobin
How is the MCH test calculated?
The MCH is calculated by dividing the total mass of hemoglobin found within a sample by the number of red blood cells found in the sample of blood. As such, MCH=(Hgb*10)/RBC. In humans, the normal range for MCH results varies from 27 to 31 picograms per cell. Converted to SI units (femtomol), this range is between 1.68 and 1.92 fmol per cell.
What other tests are needed?
The MCH blood test will usually be performed alongside an MCHC test. This calculates the amount of hemoglobin found in sample of packed red blood cells. This is calculated by dividing the hemoglobin by the hematocrit, which is the concentration of red blood cells found within the blood stream. In humans, MCHC results between 32 to 36 g/dl (or 4.9 to 5.5 mmol/L in SI units) are typical. Sometimes, the MCHC is reported as a fraction. However, the MCHC expressed in g/dl is identical to the mass fraction of hemoglobin found in blood, assuming typical red blood cell density of 1g/ml and negligible amounts of hemoglobin found in plasma. Low MCHC blood test scores indicate microcytic anemias. Macrocytic anemias will not be evident with an MCHC test, as the concentration of hemoglobin remains normal despite larger cell size. High MCHC blood test results tend to indicate hereditary spherocytosis, sickle cell disease, and homozygous hemoglobin C disease.
The MCH blood test also accompanies the MCV test, which is a measure of average red blood cell size. This allows determining whether an anemia is a microcytic anemia (where the MCV will fall below normal ranges), or a macrocytic anemia (where the MCV is above the normal range).
How is the procedure taken?
The MCH blood test is carried out by either using blood from a larger sample obtained when blood is drawn, or a small sample can be taken by pricking one’s finger with a small blood lancet. High MCH blood test results indicates a poor supply of oxygen to the blood. Low MCH blood test scores indicates a low amount of hemoglobin present in cells, possibly due to a lack of iron. This can cause health issues as tissues in the body do not receive adequate amounts of oxygen.
Levels of MCH in blood
High MCH blood test results are common in patients that:
- Have megaloblastic anemia caused by iron and folic acid deficiencies
- A family history of anemia
- Inability to recoup after severe blood loss
- Liver disorders
- Take drugs to counter AIDS
- Have negative reactions to anticonvulsant drugs
Low MCH blood test results are common when patients:
- Have vitamin C deficiencies
- Have copper deficiencies
- Are exposed to toxins like lead
- Have a family history of sideroblastic anemia or thalassemia
MCH blood test must be taken with other tests
An MCH blood test alone is nearly useless. MCH must almost always be combined with MCV and MCHC blood tests in order to ensure reliable results. In addition, MCH is generally part of a comprehensive panel called a Complete Blood Count, which provides a fairly comprehensive health overview. Among other things, the CBC (Complete Blood Count) test will check for Mean Platelet Volume, Platelet scores, Red Blood Cell Distribution Width, Hgb and Hct counts, and several tests for immune cells.
Special preparation for this test is not required unless otherwise specified by your doctor or healthcare provider. However, it is best to avoid eating fatty foods for up to 12 hours before the test, in order to achieve the most accurate results possible.