Microcytic anemia
Encyclopedia
Microcytic
anemia
(BrE
: anaemia) is a generic term for any type of anemia characterized by small red blood
cell
s. The normal mean corpuscular volume
(abbreviated to MCV on full blood count
results) is 76-100 fL
, with smaller cells (<76 fL) described as microcytic and larger cells (>100 fL) as macrocytic.
In microcytic anemia, the red blood cells (erythrocytes) are usually also hypochromic, meaning that the red blood cells are paler than usual. This can be quantified as the mean corpuscular hemoglobin or mean cell hemoglobin (MCH), the amount of hemoglobin per cell; the normal value is 27-32 picograms (pg). Similar is the mean corpuscular hemoglobin concentration
(MCHC), giving the amount of hemoglobin per volume of erythrocytes (normally about 320-360 g/L or 32-36 g/dL). Typically, therefore, anemia of this category is described as "microcytic, hypochromic anemia".
Other causes that are "typically" thought of as causing normocytic anemia
or macrocytic anemia must also be considered, and the presence of two or more causes of anemia can distort the "typical" picture of each.
The Mentzer index
is one tool used to identify the cause of microcytic anemias.
Microcyte
This is an abnormally sized red blood cell. By definition it is 5 micrometers or smaller in diameter. It is often associated with several forms of anemia.- References :...
anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
(BrE
BRE
- Computing :*Barren Realms Elite, a multi-player bulletin board system strategy game*Basic regular expression, expressions used for computerized text matching*Business rules engine, a software system to manage and execute business rules- Organisations :...
: anaemia) is a generic term for any type of anemia characterized by small red blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
s. The normal mean corpuscular volume
Mean corpuscular volume
The mean corpuscular volume, or "mean cell volume" , is a measure of the average red blood cell size that is reported as part of a standard complete blood count....
(abbreviated to MCV on full blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
results) is 76-100 fL
Femtolitre
The femto litre is the metric unit of volume equal to 10−15 litre, or one quinine cillionth or one quadrillionth litre. It is abbreviated FL or fl. One femto litre is the same as 1 μm3.1....
, with smaller cells (<76 fL) described as microcytic and larger cells (>100 fL) as macrocytic.
In microcytic anemia, the red blood cells (erythrocytes) are usually also hypochromic, meaning that the red blood cells are paler than usual. This can be quantified as the mean corpuscular hemoglobin or mean cell hemoglobin (MCH), the amount of hemoglobin per cell; the normal value is 27-32 picograms (pg). Similar is the mean corpuscular hemoglobin concentration
Mean corpuscular hemoglobin concentration
The mean corpuscular hemoglobin concentration, or MCHC, is a measure of the concentration of hemoglobin in a given volume of packed red blood cells. It is reported as part of a standard complete blood count....
(MCHC), giving the amount of hemoglobin per volume of erythrocytes (normally about 320-360 g/L or 32-36 g/dL). Typically, therefore, anemia of this category is described as "microcytic, hypochromic anemia".
Causes
Typical causes of microcytic anemia include:- childhood
- iron deficiency anemiaIron deficiency anemiaIron-deficiency anemia is a common anemia that occurs when iron loss occurs, and/or the dietary intake or absorption of iron is insufficient...
, by far the most common cause of anemia in general and of microcytic anemia in particular - thalassemiaThalassemiaThalassemia is an inherited autosomal recessive blood disease that originated in the Mediterranean region. In thalassemia the genetic defect, which could be either mutation or deletion, results in reduced rate of synthesis or no synthesis of one of the globin chains that make up hemoglobin...
- iron deficiency anemia
- adulthood
- iron deficiency anemiaIron deficiency anemiaIron-deficiency anemia is a common anemia that occurs when iron loss occurs, and/or the dietary intake or absorption of iron is insufficient...
- sideroblastic anemiaSideroblastic anemiaSideroblastic anemia or sideroachrestic anemia is a disease in which the bone marrow produces ringed sideroblasts rather than healthy red blood cells . It may be caused either by a genetic disorder or indirectly as part of myelodysplastic syndrome, which can evolve into hematological malignancies...
, congenital or acquired - anemia of chronic diseaseAnemia of chronic diseaseAnemia of chronic disease, also referred to as anemia of inflammatory response is a form of anemia seen in chronic illness, e.g. from chronic infection, chronic immune activation, or malignancy...
, although this more typically causes normochromicNormochromicNormochromic is a form of anemia in which the concentration of hemoglobin in the red blood cells is within the standard range. However, there are insufficient numbers of red blood cells. This includes: aplastic, posthemorrhagic, and hemolytic anemias and anemia of chronic disease.synonymous with...
, normocytic anemia. Microcytic anemia has been discussed by Weng et al. - lead poisoningLead poisoningLead poisoning is a medical condition caused by increased levels of the heavy metal lead in the body. Lead interferes with a variety of body processes and is toxic to many organs and tissues including the heart, bones, intestines, kidneys, and reproductive and nervous systems...
(rare) - pyridoxine deficiencyPyridoxine deficiencyPyridoxine deficiency is a paediatric disease due to a lack of pyridoxine . It usually becomes noticeable within the first 12 months of life in infants with a lack of pyridoxine, a coenzyme responsible for numerous essential metabolic reactions in humans...
- iron deficiency anemia
Other causes that are "typically" thought of as causing normocytic anemia
Normocytic Anemia
Normocytic anemia is a common issue that occurs for men and women typically over 85 years old. Its prevalence increases with age, reaching 44 percent in men older than 85 years...
or macrocytic anemia must also be considered, and the presence of two or more causes of anemia can distort the "typical" picture of each.
The Mentzer index
Mentzer index
The Mentzer index is used to differentiate iron deficiency anemia from beta thalassemia. If a CBC indicates microcytic anemia, these are two of the most likely causes, making it necessary to distinguish between them....
is one tool used to identify the cause of microcytic anemias.