From the Guidelines
Low MCV, MCH, and MCHC values are highly suggestive of iron deficiency anemia, which is a condition where the body lacks sufficient iron to produce adequate hemoglobin, and it is essential to investigate further to determine the underlying cause. When MCV and MCH are low, it typically indicates microcytic hypochromic anemia, characterized by smaller than normal red blood cells with less hemoglobin than they should have 1. The most common cause of this condition is iron deficiency anemia. Other potential causes of low MCV, MCH, and MCHC include:
- Thalassemia, an inherited blood disorder
- Anemia of chronic disease
- Sideroblastic anemia
- Lead poisoning Iron deficiency can result from:
- Inadequate dietary intake
- Poor absorption
- Blood loss, such as from heavy menstrual periods, gastrointestinal bleeding, or frequent blood donations According to the British Society of Gastroenterology guidelines for the management of iron deficiency anemia in adults, a serum ferritin level of <15 μg/L is highly specific for iron deficiency, and a cut-off of 45 μg/L provides a respectable specificity of 0.92 1. If you have low MCV, MCH, and MCHC values, your doctor will likely recommend further testing to determine the underlying cause, which may include:
- Iron studies
- Ferritin levels
- Possibly tests for thalassemia, such as Hb electrophoresis, especially if there is an appropriate ethnic background and microcytosis with normal iron studies 1 Treatment typically addresses the underlying cause - for iron deficiency, this usually means iron supplementation through diet or supplements containing ferrous sulfate, ferrous gluconate, or ferrous fumarate, typically taken for several months until blood values normalize.
From the Research
Low MCV, MCH, and MCHC Values
- Low MCV (Mean Corpuscular Volume) values, typically less than 83 micron^3, indicate the presence of small red blood cells, which is a characteristic of microcytic anemia 2.
- Low MCH (Mean Corpuscular Hemoglobin) and MCHC (Mean Corpuscular Hemoglobin Concentration) values are also indicative of microcytic anemia, as they suggest a decrease in the amount of hemoglobin in the red blood cells 3.
- The most common cause of microcytic anemia is iron deficiency anemia (IDA), which can be due to abnormal bleeding, rapid growth, or inadequate diet 4.
Causes of Microcytic Anemia
- Iron deficiency anemia (IDA) is the most common cause of microcytic anemia, and it can be diagnosed by measuring serum ferritin levels 5.
- Other causes of microcytic anemia include thalassemia, congenital sideroblastic anemia, and hemoglobinopathy E 5.
- The presence of ringed sideroblasts is characteristic of sideroblastic anemia, while increased HbA2 levels are diagnostic for beta-thalassemia 5.
Diagnostic Tests
- Serum iron, total iron binding capacity, transferrin saturation, serum ferritin, and serum transferrin receptor are tests used to assess iron deficiency 5.
- Hemoglobin electrophoresis is required for the diagnosis of hemoglobinopathy E 5.
- The microcytic to hypochromic RBC ratio can be used as a discriminant index to distinguish between thalassemia and iron deficiency anemia 6.
Treatment
- Oral iron supplements are usually effective in treating iron deficiency anemia, while parenteral iron therapy may be necessary in cases of malabsorption or intolerance to oral iron 2, 5.
- The optimal therapeutic regimen for iron deficiency anemia involves administering 100 mg of elemental iron twice daily, separately from meals 5.