Anemia is a common blood disorder, which is caused when there is a drop in hemoglobin or hematocrit in the blood.
In anemia, the red blood cell (RBC) level in the blood is low. RBCs carry oxygen to the tissues. Therefore, if RBCs are low, the body’s tissues suffer from a lack of oxygen. Anemia is common in cancer patients and may be a result of the tumor itself or of the cancer treatment.
RBCs are produced in the bone marrow and circulate in the blood until they become too old and are removed by the spleen. Anemia can result from excessive RBC loss due to bleeding or insufficient RBC production by the bone marrow. If the cells are excessively destroyed in the blood or spleen, hemolytic anemia is present.
Anemia is a symptom of many underlying diseases. The most common are iron deficiency, acute blood loss, and inflammatory diseases such as rheumatoid arthritis.
Hemoglobin is the part of blood that distributes oxygen from the lungs to tissues in the body. Hematocrit is the measurement of the percentage of red blood cells found in a specific volume of blood.
Anemia is often a symptom of a disease rather than a disease itself.
Anemia usually develops because of excessive blood loss or hemorrhaging, deficient production of red cells, excessive red cell destruction both decreased production and excessive destruction of red cells
Hypoproliferative anemia : Hypoproliferative anemia can be subdivided into three classes based upon the size of the RBCs. The cells may be larger than normal (macrocytic), normal (normocytic), or smaller than normal (microcytic).
Macrocytic anemia : Macrocytic anemia can be due to several causes. The first is a deficiency in vitamin B12 or folate, both important ingredients in RBC production. Please see Vitamin B12 Insufficiency and Folic Acid Insufficiency. It may also be caused by disease of the bone marrow such as myeloproliferative disorders, inherited bone marrow diseases, or cancer. Please see Myeloproliferative Disorders and Leukemia.
Normocytic anemia : Normocytic anemia may be due to chronic disease including malnutrition or mixed anemia (combined macrocytic and microcytic anemia).
Microcytic anemia : Microcytic anemia is due to abnormalities in the production of the essential RBC protein, hemoglobin. This is often to due to underlying disease, such as thalassemia.
Hemolytic anemia : Hemolytic anemia may be due to inherited abnormal hemoglobin (the essential RBC protein; for example, sickle cell anemia), prosthetic heart valves, infections such as malaria, and disease such as thrombotic thrombocytopenia purpura and hemolytic-uremic syndrome.
Anemia can affect the body rapidly or be a slow-developing process. If it is due to rapid blood loss or acute hemolysis, the anemic patient will experience lightheadedness (due to low blood pressure), weakness, and cardiac strain (with shortness of breath and shooting pains from the chest). More gradual onset of anemia (chronic anemia) is accompanied by fatigue, irritability, headache, pain, palpitations (fluttering of heartbeat), difficulty in breathing especially when lying flat, decreased body temperature, and elevated heart rate among other symptoms.
Generally the symptoms of anemia are a result of the decrease of oxygen in the cells or "hypoxia". Because red blood cells, as hemoglobin, carry oxygen, a decreased production or number of these cells result in "hypoxia." Many of the symptoms will not be present with mild anemia, as the body can often compensate for gradual changes in hemoglobin.
The following are the most common symptoms of anemia. However, each individual may experience symptoms differently. Symptoms may include:
Abnormal paleness or lack of color of the skin, increased heart rate (tachycardia), breathlessness, or difficulty catching a breath (dyspnea), lack of energy, or tiring easily (fatigue), dizziness, or vertigo, especially when standing, headache
irritability, irregular menstruation cycles, absent or delayed menstruation (amenorrhea), sore or swollen tongue (glossitis)
jaundice, or yellowing of skin, eyes, and mouth, enlarged spleen or liver (splenomegaly, hepatomegaly), impaired wound and tissue healing.
The symptoms of anemia may resemble other blood disorders or medical problems. Because anemia is often a symptom associated with another disease, it is important for your physician to be aware of symptoms you may be experiencing.
Generally, anemia may be caused by several problems, like infections, certain diseases, certain medications, poor nutrition, blood loss.
There are several different types of anemia, each with a specific cause and treatment like iron-deficiency anemia, megaloblastic (pernicious) anemia, anemia of folate deficiency, hemolytic anemia, sickle cell anemia, Cooley's anemia, aplastic anemia, chronic anemia.
Aplastic anemia occurs when the bone marrow produces too few of all three types of blood cells: red blood cells, white blood cells, and platelets. A reduced number of red blood cells causes hemoglobin to drop. A reduced number of white blood cells makes the patient susceptible to infection. And, a reduced number of platelets causes the blood not to clot as easily.
Hemolytic anemia is a disorder in which the red blood cells are destroyed faster than the bone marrow can produce them. The term for destruction of red blood cells is hemolysis. There are two types of hemolytic anemia, including the following:
Intrinsic - the destruction of the red blood cells due to a defect within the red blood cells themselves. Intrinsic hemolytic anemias are often inherited, such as sickle cell anemia and thalassemia. These conditions produce red blood cells that do not live as long as normal red blood cells.
Extrinsic - red blood cells are produced healthy but are later destroyed by becoming trapped in the spleen, destroyed by infection, or destroyed from drugs that can affect red blood cells.
The most common cause of anemia is iron deficiency. Iron is needed to form hemoglobin. Iron is mostly stored in the body in the hemoglobin. About 30 percent of iron is also stored as ferritin and hemosiderin in the bone marrow, spleen, and liver.
Megaloblastic (Pernicious) Anemia
Megaloblastic (pernicious) anemia is a rare disorder in which the body does not absorb enough vitamin B12 from the digestive tract, resulting in an inadequate amount of red blood cells (RBCs) produced.
Sickle Cell Anemia
Sickle cell disease is an inherited blood disorder characterized by defective hemoglobin. It affects millions of people throughout the world.Normal hemoglobin cells are smooth and round, allowing for ease in moving through blood vessels. Sickle cell hemoglobin molecules are stiff and form into the shape of a sickle or a scythe. They tend to cluster together, and cannot easily move through blood vessels. The cluster causes a blockage and stops the movement of oxygen-carrying blood.
Sickle cells die after about 10 to 20 days, unlike normal hemoglobin cells, which live for up to 120 days. This results in a chronic short supply of red blood cells, which causes anemia.