Anemia Types

Anemia is generally defined as a reduction in the number or volume of circulating red blood cells (erythrocytes) or an alteration in hemoglobin. Technically, anemia is not a disease but a symptom of any number of disorders. There are over 400 types of anemia, but many of them are rare. Even more startling is the fact that, presently, more than half of the world’s population will experience some form of anemia in their lifetime.

Generally, the origin of anemia is classified as either nutritional or non-nutritional. Anemias of a nutritional origin are those that stem from a deficiency of some nutrient, mainly iron, vitamin B12, or folic acid (folacin or folate); 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.

Anemia is frequently associated with scurvy and may be indicative of a folate deficiency (macrocytic) or an iron deficiency (hypochromic). Nevertheless, patients have responded well with just the addition of vitamin C alone, suggesting that there may be a role that ascorbate plays in the maintenance of normal pools of reduced folates. However, there is no real evidence to suggest that folate is ascorbate dependent. In the case of iron deficiency, though, it is known that adding vitamin C will increase iron absorption.

Anemias can be classified using two basic approaches:

An etiologic classification is based on the various conditions that can result from any of the physiologic changes and helps determine direction for planning care. A morphologic classification provides an orderly method for ruling out certain diagnoses when establishing a cause for a particular anemia.

Such morphologic changes in the red blood cell are described in this manner:

These changes produce the following categories of anemias:

Macrocytic-normochromic anemia, also known as megaloblastic anemia, produces large, abnormally shaped erythrocytes but normal hemoglobin concentrations. The unusually large stem cells (megaloblasts) in the bone marrow mature into abnormally large erythrocytes (macrocytes) in the circulation. Megaloblastic stem cells are larger at all maturational stages than normal stem cells (normoblasts). In addition, the nucleus of the megaloblast is unusually small in relation to the size of the cell. As the cell matures and begins to synthesize hemoglobin, chromatin in the nucleus fails to clump normally, although the hemoglobin content remains normal. Defective DNA synthesis, caused by deficiencies of vitamin B12 or folate, produces a pattern of ineffective erythropoiesis (cell formation), causing premature cell death with reduced numbers of mature erythrocytes. It is unknown why such a deficiency would cause this outcome, but suggested mechanisms include a delay in nuclear maturation and an imbalance in the normal distribution of RNA and DNA. Nuclear functions or DNA replication and cell division are blocked or delayed. However, RNA and protein synthesis, both cytoplasmic functions proceed normally. The imbalance in the RNA/DNA ratio causes derangement of cell growth.

Microcytic-hypochromic anemia produces small, abnormally small erythrocytes and reduced hemoglobin concentrations. However, hypochromia can occur even in cells of normal size. This type of anemia results from a variety of conditions that are caused by disorders of iron metabolism, porphyrin and heme synthesis, or globin synthesis.

Normocytic-normochromic anemia produces a destruction or depletion of normal or mature erythrocytes. Although the erythrocytes are relatively normal in size and in hemoglobin content, they are insufficient in number. This type does not share any common cause, pathologic mechanism, or morphologic characteristics and is less common than the others. The five distinct anemic conditions exemplify the diversity of this classification.

Data used to identify anemia types include the erythrocyte indicators:

Anemias associated with decreased RBCs can occur for any number of reasons. Some anemias arise from failure or inability of the bone marrow to synthesize RBCs properly. Others occur because the body cannot synthesize or absorb a specific component necessary for RBC production. Such anemias resulting from a decreased production of RBCs include iron deficiency anemia, Vitamin B12 (pernicious) anemia, folic acid deficiency anemia, and aplastic anemia. Of those suffering from anemia, 20% are women and 50% are children.

Anemia is sometimes the first detectable sign of arthritis, infection, or certain major illnesses, including cancer. Drug use, hormonal disorders, chronic inflammation in the body, surgery, infections, peptic ulcers, hemorrhoids, diverticular disease, heavy menstrual bleeding, repeated pregnancies, liver damage, thyroid disorders, rheumatoid arthritis, bone marrow disease, and dietary deficiencies can all lead to anemia. There are also a number of hereditary disorders that cause anemia, especially sickle cell disease and thalassemia.

According to the Iron Institute, who gathered definitions from medical dictionairies and encyclopedias as well as the internet, anemia has a wide variety of definitions. Even though all of them are correct to some extent, none of them is a complete definition. The following are just a few which will explain why it is so difficult to umbrella over 400 anemias into one convenient description. Anemia is:

Literally, “anemia” means without blood! This is also an absurd definition because people cannot live without blood, but they can live with anemia.

Symptoms of anemia often go unrecognized. The first signs of its development may be a loss of appetite, constipation, headaches, noises in the ears, irritability, and/or difficulty concentrating or with memory. Established anemia produces such symptoms as weakness, fatigue, coldness of the extremeties, depression, dizziness, overall pallor (pale complexion), pale and brittle nails (lack of iron), pale lips and eyelids, pallor in the palms of the hands, soreness in the mouth, restless leg syndrome, and a cessation of menstruation and/or a loss of libido. Pallor results when blood flow is diverted away from the skin, or other areas, in order to meet the more critical needs of the body, as the brain and heart.

These symptoms are caused by the inability of anemic blood to supply body tissues with enough oxygen. Activity intolerance is a common problem since physical activity increases the demand for oxygen. If there are not enough oxygen-circulating erythrocytes to provide sufficient oxygen, individuals become physically weak and unable to engage in normal physical activity without experiencing profound fatigue. In very advanced cases, swelling of the ankles and other evidence of heart failure may appear.

Although pallor of the skin is a sign of anemia, it is not the most reliable sign because many other factors can affect complexion and skin color. When pallor of the skin, nail beds, and conjunctiva are all noticed, the cause is likely anemia. Jaundice of the skin and sclera can occur as a result of hemolysis and the release of bilirubin into the blood stream where it eventually finds its way into the skin and mucous membranes. Bleeding under the skin and bruises in response to the slightest trauma often are present in anemic and leukemic patients. A bluish tint to the skin (cyanosis) can indicate hypoxia caused by inadequate numbers of oxygen-carrying erythrocytes.

Swollen and bleeding gums can occur as a result of nutritional deficiencies and inadequate blood supply to mucous membranes. Breakdown of the oral mucosa can further aggravate anemia by making chewing, tongue movements, and swallowing difficult.

Bleeding into the joints is not unusual in certain kinds of anemia, especially sickle cell disease. Patients may report joint pain or they may be observed moving more slowly than usual and with apparent discomfort. In addition, the joints appear red and swollen.

Until recently, RLS (restless leg syndrome) was basically ignored as being a symptom of anything despite it being a revalent disorder affecting up to 15% of adult populations. The syndrome is characterized by a strong urge to move the extremeties that usually becomes worse at night, peaking somewhere in the middle of the night. While much of the clinical intervention has focused on the dopaminergic system (dopamine is a chemical synthesized by the adrenals), there is a growing body of evidence that suggests an iron deficiency cause. High dose, intravenous iron therapy brought on complete relief of symptoms in 21 out of 22 RLS patients for periods of three to nine months, even though the majority had normal iron levels prior to treatment.

When anemia is severe or sudden in onset, peripheral blood vessels constrict so as to direct available blood flow chiefly to the vital organs. A number of systemic symptoms result from this lifesaving maneuver.

Some types of anemia include the following: