Anemia & Types of Anemia

Anemia is defined as a reduction in the number or volume of circulating red blood cells (erythrocytes) or an alteration in the hemoglobin. Anemia as such is not a disease but a symptom of a number of disorders. One might be amazed to know that there are over 400 types of anemia though many of which are extremely rare but they have been described in medicine. Even more startling is the fact that almost half of the world’s population will experience some form of anemia in their lifetime.

Anemia in broad terms is classified as either nutritional or non-nutritional.

Anemias of a nutritional origin arise from a deficiency of some nutrient, mainly iron, vitamin B12, or folic acid; but they can also result from a deficiency of other nutrients, including vitamins B2, B6, C, A, D, E, and K; as well as zinc, copper, calcium, and protein. The lack of certain enzymes can also cause anemia.

Non-nutritional causes are those that produce a decreased development of the red blood cell (RBC) precursors, decreased erythropoiesis (erythrocyte formation), or an increase in the destruction of RBCs.

Etiology: the actual cause for erythrocyte and hemoglobin depletion

Morphology: the characteristic changes in the size, shape and color of red blood cells.

Such morphologic changes in the red blood cells are as follows:

Cell size:
normocytes (normal)
microcytes (smaller than normal)
macrocytes (larger than normal)
anisocytes (various sizes)

Cell shape:
poikilocytes (irregularly-shaped cells)
spherocytes (globular cells)
drepanocytes (sickle cells)

Cell color:
normochromic (sufficient or normal amounts of hemoglobin)
hyperchromic (containing an unusually high concentration of hemoglobin in its cytoplasm)
hypochromic (containing an abnormally low concentration of hemoglobin)

These changes usually produce the following types of anemias:
Macrocytic-normochromic anemia
Microcytic-hypochromic anemia
Normocytic-normochromic anemia

Macrocytic-normochromic anemia, also known as megaloblastic anemia, produces large, abnormally shaped erythrocytes but normal hemoglobin concentrations. The unusually large stem cells called as megaloblasts in the bone marrow mature into abnormally large erythrocytes (macrocytes) in the circulation.

Microcytic-hypochromic anemia produces abnormally small erythrocytes and reduced hemoglobin concentrations.

Normocytic-normochromic anemia produces a destruction or depletion of normal or mature erythrocytes though the erythrocytes are relatively normal in size and in hemoglobin content.

Symptoms:

Symptoms of anemia often go unrecognized till they reach a more ominous stage. The first signs usually are loss of appetite, constipation, headaches, noises in the ears, irritability, difficulty concentrating, weakness, fatigue, depression, dizziness, overall pallor, pale and brittle nails, pale lips and eyelids, pallor in the palms of the hands, and most importantly a cessation of menstruation and/or a loss of libido in its later stages.

Other Types of Anemia:

Some other types of anemia include:

• Aplastic anemia is where bone marrow may or may not have adequate cells but it still fails to produce adequate numbers of RBC. Autoimmune hemolytic anemia (AIHA) can be of various types and covers a large group of anemias involving auto-antibodies against red cell antigens.
• Achrestic anemia is a type of megaloblastic type, morphologically resembling pernicious anemia but due to other causes.
• Cooley's anemia is the homozygous form of beta-thalassemia.
• Deficiency anemia refers to a nutritional deficiency that causes anemia like iron deficiency anemia.
• Drug-induced immune hemolytic anemia is an immune hemolytic anemia caused by drugs such as penicillin.
• Hemolytic anemia may be hereditary or acquired and usually results from an infection or chemotherapy, or occurs as part of an autoimmune process. Hypochromic anemia occurs when there is a decrease in hemoglobin that is proportionately much greater than the decrease in the number of erythrocytes.
• Hypoplastic anemia is due to the incapability of blood forming cells.
• Hypoplastic congenital anemia, also called erythrogenesis imperfecta and Fanconi's syndrome, is an idiopathic progressive form occurring in the first year of life and without leukopenia and thrombocytopenia.
• Iron-deficiency anemia is characterized by low or absent iron stores, low serum iron concentration, low transferrin saturation, elevated transferrin, low hemoglobin concentration or hematocrit, and hypochromic and microcytic red blood cells.
• Lederer's anemia is one form of acute hemolytic anemia of short duration.
• Macrocytic anemia results when the erythrocytes become much larger than normal.
• Mediterranean anemia
• Megaloblastic anemia is characterized by the presence of megaloblasts in the bone marrow.
• Microcytic anemia is characterized by a decrease in size of erythrocytes.
• Myelopathic or myelophthisic anemia is caused by the destruction or crowding out of hematopoietic tissues by space-occupying lesions.
• Normochromic anemia occurs despite the hemoglobin content of the red blood cells, as measured by the MCHC (mean corpuscular hemoglobin concentration), is still within the normal range.
• Normocytic anemia is characterized by proportionate decreases in hemoglobin, packed red cell volume, and the number of erythrocytes per cubic millimeter of blood.
• Nutritional anemia, also known as "deficiency anemia", is caused by a deficiency of an essential substance in the diet, and may be caused by poor dietary intake or by malabsorption.
• Pernicious anemia is a serious form that results from a lack of vitamin B12, generally because of a decreased secretion by the gastric mucosa of IF (intrinsic factor) essential to the formation of erythrocytes and the absorption of vitamin B12.
• Sickle cell anemia, sometimes called sickle cell disease, is a genetically determined defect of hemoglobin synthesis.
• Spur-cell anemia occurs when the red cells have a bizarre spiculated shape and are destroyed prematurely, primarily in the spleen.
• Von Jaksch’s anemia, also known as pseudoleukemica infantum, is an anemic leukemia of infants. It is a syndrome caused by many factors such as malnutrition, chronic infection, and malabsorption.