A high mean corpuscular volume (MCV) level means that red blood cells have a larger than average size. An elevated mean corpuscular hemoglobin (MCH) level indicates higher than normal hemoglobin levels in red blood cells.
MCV refers to the volume of red blood cells in the body, which are measured in femtoliters. MCV readings are taken from a blood cell sample. A typical range for MCV is somewhere between 80 and 96 femtoliters, although that number varies slightly based on the laboratory performing the test. MCH considers hemoglobin levels in a person's red blood cells. MCV and MCH are taken as part of a complete blood count, or a CBC. They are part of a red blood cell index (RBC) that is included in the CBC. In addition to these factors, the RBC includes a test for the volume of hemoglobin in relation to the size of the cell, or the hemoglobin concentration per red blood cell. RBC results can help doctors identify the underlying cause of anemia, which arises when a person has too few red blood cells.
What Elevated MCV Levels Mean
Sometimes, slightly elevated levels of MCV and MCH are clinically insignificant but they can also signal a serious underlying problem. An MCV reading that exceeds 100 femtoliters is called macrocytosis, and it can result from several conditions. Macrocytosis that exists alongside anemia is called macrocytic anemia. This condition can be caused by a deficiency in vitamin B12, which is also called folic acid. Some medications can raise MCV levels, as can excessive alcohol use. Some blood cancers cause macrocytosis. Occasionally, macrocytosis appears in patients whose blood supplies are returning to normal levels after being depleted during surgery.
What Elevated MCH Levels Indicate
The MCH test shows hemoglobin levels in red blood cells. Hemoglobin helps red blood cells transport oxygen. Normal MCH levels range between 26 and 33 picograms of hemoglobin per red blood cell. An MCH level is considered high if it rises above 34 picograms. As with elevated levels of MCV, a high MCH reading usually indicates a folic acid deficiency. Folic acid is important for helping the body carry out basic processes. A person who has macrocytic anemia cannot produce enough blood cells, which means that they have a lower hemoglobin ratio than normal in their red blood cell count. In addition to anemia, an elevated MCH level can result from other factors. Level of hydration can influence MCH readings, as can time of day. The threshold for normal MCH levels also varies based on gender and age.
Sometimes, people are given a complete blood count test if they display signs of anemia, which include weakness and fatigue. Other symptoms include headache, dizziness, pale skin and cold hands and feet. Mild anemia might not produce any symptoms, while severe anemia can make it hard to perform normal activities. Over time, anemia can cause heart arrhythmias. It can damage organs in the body that are deprived of oxygen. Anemia can cause fluid loss, which can be life-threatening in extreme cases. The risk of complications from anemia rises with the presence of other illnesses such as cancer, kidney disease and HIV/AIDS.