Background
Anemia is a medical condition in which the number of red blood cells (RBCs) – also called the RBC count — or the amount of hemoglobin is less than normal. Hemoglobin is a reddish, iron-containing protein found in red blood cells that gives the red color to blood. Hemoglobin combines with oxygen from the lungs and then transports the oxygen to cells throughout the body. Anemia is the most common blood disease. There are more than 400 different types of anemia, but many of them have different causes, treatments, and outlooks.
Anemia is often treated using blood transfusions, usually from donor blood. More than 40,000 blood donations are performed every day in the United States, and over 5 million Americans receive a blood transfusion each year.
Risks
The incidence of anemia increases with age, particularly after age 65. Risk factors associated with the condition include:
Symptoms
Symptoms of anemia are usually caused by hypoxia — a reduced amount of oxygen delivered to the cells and tissues of the body. Fatigue is the main complaint of anemia, but some types of the disease, including very mild anemia, have no symptoms. Anemia symptoms may vary from mild to intense and include:
Symptoms of worsening anemia may include:
Causes and Types
Anemia is caused by a process involving damage or destruction of red blood cells that results in low hemoglobin levels. The general causes that can lead to anemia include:
The types of anemia can be divided into three main groups:
I) Anemia due to blood loss
II) Anemia caused by decreased or impaired red blood cell production
III) Anemia caused by high rates of red blood cell destruction
Anemia may be classified according to the Mean Corpuscular Volume (MCV), also known as the mean cell volume. The MCV is a measurement of the average red blood cell size, measured in units of femtoliters (fL), detected in a standard complete blood count. The MCV classification system helps doctors determine the underlying cause of the anemia. A low MCV (less than 80 fL) is called microcytic anemia (low cell volume). An MCV in the normal range (80-99 fL) is considered a normocytic anemia (normal cell volume). A high MCV (above 99 fL) is categorized as a macrocytic anemia (large cell volume).
The World Health Organization (WHO) defines anemia as a hemoglobin level of less than 13 g/dL in men and less than 12 g/dL in women.
Acute anemia is associated with an abrupt drop in hemoglobin to a level of 7-8 g/dL along with symptoms. In chronic anemia, hemoglobin levels of 4-5 g/dL may be tolerated.
All types of anemia can be categorized under the three general groups. Some of the most common forms of anemia are classified, based on the cause of the disease, as follows:
I. Anemia due to blood loss
– Iron-poor diet
– Certain drugs, foods, and caffeinated beverages
– Endurance training
– Exacerbation of anemia in an anemic patient after blood loss during a surgical operation (such as a hysterectomy) that is unrelated to anemia
Acute blood loss anemia has a wide range of causes such as:
– Traumatic injury (damage to the brain)
– Massive upper or lower gastrointestinal (GI) bleeding hemorrhage
– Chronic conditions, including cancers such as mesothelioma
– Chemotherapy for cancer treatment
– Ruptured ectopic pregnancy
– Ruptured aneurysm
– Disseminated intravascular coagulation (DIC) (thrombosis followed by bleeding due to various types of illnesses)
– Hemoglobinopathy (abnormal hemoglobin production) in severe sickle cell anemia
– Congenital bleeding disorders (such as Von Willebrand disease and Hemophilia A)
– Autoimmune hemolytic anemia (impaired RBCs that lead to loss of RBCs in patients with conditions such as lupus, certain types of lymphoma and leukemia
– Acquired platelet disorder
II. Anemia caused by decreased or impaired red blood cell production
III. Anemia caused by high rates of red blood cell destruction
Diagnosis
Anemia is diagnosed through a physical exam by the doctor as well as through blood tests to identify a specific type of anemia that may be present. Blood tests may include:
Other laboratory tests — liver function tests, kidney function test, and bone marrow biopsy — also may be performed.
Treatment
Treatment of anemia varies widely, depending on the cause and severity of the condition. The type of anemia must first be correctly determined before the proper treatment can be started. Since the treatment for anemia is always based on the specific type of disease, it is imperative that a qualified doctor make an exact diagnosis.
Mild anemia with no or minimal symptoms may be due to low iron levels and can be treated with iron supplements. Vitamin B12 injections are required for patients with pernicious anemia. Patients with severe types of anemia may need to be hospitalized. A rapidly bleeding stomach ulcer is treated with both medications to heal the ulcer and a blood transfusion to replace the depleted red blood cells, thereby reducing the symptoms of anemia. A patient who has sustained an injury may require a blood transfusion to correct extensive blood loss. Replenishing the patient’s blood improves symptoms of anemia.
Chemotherapy for cancer may cause bone marrow damage, and bone marrow damage can lead to anemia. Patients who are undergoing chemotherapy for cancer or who have bone marrow disease often require medications such as epoetin alfa to stimulate the production of red blood cells in bone marrow production. An elevated number of red blood cells increases the amount of hemoglobin in the blood so that more oxygen can be transported to tissues throughout the body.
Anemia treatments may include:
Possible Complications
Anemia may be associated with negative health outcomes such as:
In severe anemia, the hemoglobin level may fall too low and reduce the amount of oxygen delivered to all of the tissues. Low levels of oxygen (hypoxia) in vital organs such as the heart may result in cardiovascular complications. Arrhythmias — problems with the rate or rhythm of the heartbeat — associated with anemia such may trigger a heart attack.
Prognosis
The prognosis, or outlook, of anemia is often good, depending upon the type and specific cause of the disorder. The severity of anemia, patient’s age, patient’s health, and patient’s compliance with treatment will affect recovery. The outcome is usually better in younger people than in elderly people. Anemia due to chronic medical conditions such as kidney failure, heart disease or lung disease may be more severe and usually requires ongoing, long-term monitoring and treatment.
Prevention
A healthy lifestyle, including an appropriate diet, limited alcohol use, and regular medical checkups for blood tests can help to prevent anemia or, for those already diagnosed with the condition, keep it under control. Patients with sickle cell anemia or other chronic conditions should be monitored by medical professionals on a regular basis.
Anemia is a potentially serious condition because it may be linked with another underlying disease. If you have any signs and symptoms of anemia – fatigue, low energy, weakness, lightheadedness, shortness of breath, unusual bleeding — consult a medical doctor immediately for a full evaluation, including proper testing.
References