From the Guidelines
Anemia with low MCV, MCH, and MCHC typically indicates microcytic hypochromic anemia, most commonly caused by iron deficiency. This condition occurs when red blood cells are smaller than normal (microcytic) and contain less hemoglobin than normal (hypochromic) 1. The most frequent cause is iron deficiency, but other potential causes include thalassemia, anemia of chronic disease, sideroblastic anemia, and lead poisoning.
Key Points to Consider
- Iron deficiency usually develops gradually due to inadequate dietary iron intake, poor iron absorption, or chronic blood loss (such as from heavy menstrual periods, gastrointestinal bleeding, or frequent blood donations) 1.
- Treatment typically involves oral iron supplements like ferrous sulfate 325 mg taken 1-3 times daily between meals with vitamin C to enhance absorption 1.
- Therapy should continue for 3-6 months even after blood counts normalize to replenish iron stores.
- Patients should be evaluated for the underlying cause of iron deficiency, particularly occult bleeding.
- Side effects of iron supplementation may include constipation, nausea, and black stools.
- In severe cases or when oral therapy isn't tolerated, intravenous iron formulations may be necessary.
- The body needs iron to produce hemoglobin, the protein in red blood cells that carries oxygen, which explains why insufficient iron leads to smaller cells with less hemoglobin content 1.
Diagnostic Approach
- Automated cell counters provide measurements of the changes in red cells that accompany iron deficiency, including reduced mean cell Hb (MCH) and mean cell volume (MCV) 1.
- Serum markers of iron deficiency include low ferritin, low transferrin saturation, low iron, raised total iron-binding capacity, raised red cell zinc protoporphyrin, increased serum transferrin receptor (sTfR), low reticulocyte Hb (Retic-Hb), and raised percentage hypochromic red cells 1.
Management and Prevention
- Management of anemia in adult critical care patients involves a diagnostic flow-chart to guide the workup and treatment of anemia, including iron profile workup, ferritin, TSAT, and reticulocyte count 1.
- Prevention of anemia in critical care patients includes procedures designed to prevent the development of anemia, such as minimizing blood loss and optimizing oxygen delivery.
From the Research
Anemia with Low MCV, MCH, and MCHC
Anemia characterized by low Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), and Mean Corpuscular Hemoglobin Concentration (MCHC) is typically indicative of microcytic anemia. This condition is defined by the presence of small, often hypochromic, red blood cells in a peripheral blood smear, usually with an MCV of less than 80-83 micron^3 2, 3.
Causes of Microcytic Anemia
The most common cause of microcytic anemia is iron deficiency anemia, which can be managed with oral or intravenous iron, depending on the severity and comorbid conditions of the affected individual 2, 3. Other causes include:
- Thalassemia, a group of genetic disorders affecting hemoglobin synthesis
- Sideroblastic anemia, characterized by the accumulation of iron in the mitochondria of red blood cell precursors
- Anemia of chronic disease, which can be associated with chronic infections, inflammation, or malignancies
Diagnostic Considerations
While MCV can help guide the diagnosis of anemia, it is essential to consider other laboratory tests and clinical factors to determine the underlying cause of microcytic anemia 4, 5. For instance, iron deficiency anemia can be distinguished from anemia of chronic disease by measuring serum ferritin, iron concentration, and transferrin saturation 2. Additionally, the presence of other deficiencies, such as vitamin B12 or folic acid deficiency, can mask or complicate the diagnosis of iron deficiency anemia 5.
Interference with MCHC Measurements
It is also important to note that MCHC measurements can be affected by interfering factors, such as cold agglutination or lipid blood interference, which can lead to false elevations 6. Therefore, it is crucial to consider these potential interferences when interpreting MCHC results and to use effective methods to correct for them.