You are probably familiar with the fact that the term anemia refers to a blood disorder in which the account of healthy red blood cells is lower than normal (or the red blood cells do not contain enough hemoglobin), and that there are many types of this disorder. One of them is hemolytic anemia. Hemolytic anemia is a disorder in which the red blood cells are eliminated from the bloodstream earlier than normal. This early destruction of red blood cells does not happen without some underlying cause. There often exists a disease or some kind of disorder which causes the destruction of red blood cells, unless the disorder was inherited.
In order for us to give you a more detailed explanation, we first have to familiarize you with the function of red blood cells (Erythrocytes).

Red blood cells are mostly made of hemoglobin (an iron and protein compound). They are produced in the bone marrow and their lifetime is usually 3 – 4 months. They die under the attack of macrophages in the liver and spleen. When they are destroyed, they release iron for the liver to store and use. Their main function is to carry oxygen from the lungs to the cells in your body and this is made by hemoglobin which captures oxygen and delivers it to every cell in your body.

In hemolytic anemia, the bone marrow is unable to produce enough healthy red blood cells since they are being destroyed too early.
Hemolytic anemia has many types and they may be acquired or inherited. Inherited types of hemolytic anemia are passed on by the parents and they are conditions which you have to deal with all your life. In the case of inherited hemolytic anemias, the passed on gene/s that control the production of the red blood cells are faulty. Some types of inherited hemolytic anemia are:

1. Thalassemias

Thalassemias are inherited blood disorders in which certain types of hemoglobin are not produced in sufficient quantities by the body. Therefore, the body produces less healthy red blood cells than usual. There are certain groups that are more at risk of developing thalassemias than others. These include people of Indian, Chinese, Filipino, Mediterranean, Southeast Asian or African descent.

2. Sickle Cell Anemia – More about Sickle Cell Anemia here

Sickle cell anemia is a severe disease in which the body produces abnormal hemoglobin, which causes an abnormal, (sickle) shape of the red blood cells. These erythrocytes die after 10 to 20 days, while the normal, healthy red blood cells live for approximately 120 days, and the bone marrow is not able to produce healthy red blood cells fast enough.

3. Hereditary Spherocytosis and Elliptocytosis

In this condition, the erythrocyte membrane surface that determines the shape of the sphere carries a defect, which causes the red blood cells to have a sphere shape. These erythrocytes also have a shorter lifespan. The condition is mostly present in persons of Northern European descent. Similar to this, hereditary elliptocytosis also includes a membrane surface defect which causes the red blood cells to have an elliptic shape. The cells also die earlier than normal and are not flexible as healthy red blood cells.

4. Deficiency of glucose-6-phosphate dehydrogenase (G6PD)

Red blood cells with this condition lack a highly important enzyme called G6PD which is normally a part of the erythrocytes. In this condition, the red blood cells which lack G6PD burst and die if they encounter certain substances. It is less common in Caucasians than in African Americans.

Acquired hemolytic Anemias

As opposed to hereditary hemolytic anemias, acquired hemolytic anemias are treatable conditions which may disappear if the underlying cause is properly treated. Acquired hemolytic anemias may have a disease or some other factor that causes the early destruction of the red blood cells.

Immune Hemolytic Anemia

In immune hemolytic anemias, the destruction of the red blood cells is caused by the body’s immune system. Immune hemolytic anemias may be alloimmune, autoimmune and drug-induced.

1. Alloimmune hemolytic anemia.

Here, the body produces antibodies against erythrocytes that were received through a blood transfusion. This happens when the patient receives blood that is a different type than their own.

Alloimmune hemolytic anemia can also happen in pregnancy. If a woman’s blood is Rh-negative, and her baby’s blood is Rh positive, then there is a chance that this type of anemia will appear.

2. Autoimmune hemolytic anemia (AIHA). 

Autoimmune hemolytic anemia can appear very quickly and cause serious consequences in a short period of time. In this condition, the immune system produces antibodies that attack the red blood cells. The reason for this is unknown. However, there are some diseases and infections that can increase the risk of developing autoimmune hemolytic anemia. These include autoimmune diseases, certain blood cancers, chronic lymphocytic leukemia, certain viruses such as HIV and hepatitis. It may also develop after a patient has had a marrow and blood stem cell transplant.
The antibodies that the immune system produces are in some cases called warm and cold antibodies. Warm antibodies destroy red blood cells at warm temperatures and cold antibodies destroy them at cold temperatures. Autoimmune hemolytic anemia with cold antibodies is less common than the warm antibody AIHA.

3. Drug-induced hemolytic anemia

Hemolytic anemia may also be caused by a reaction to certain medicines, such as penicillin, acetaminophen, quinine, antimalarial and anti-inflammatory medicines, etc.

Acquired Hemolytic Anemias may also appear under the physical damage of the cell membranes of the erythrocytes. The damage may be caused in various ways. For example, it might appear due to changes in the small blood vessels or under the influence of malignant hypertension. It may also appear as a result of performing arduous physical activities.

In each type, acquired or inherited, the body produces abnormal erythrocytes (red blood cells).

The symptoms and treatment of hemolytic anemia

The symptoms of hemolytic anemia can be barely noticeable in some cases, whereas in other cases they may be quite severe and hard to deal with.

Any type of anemia is usually followed by a common symptom: physical fatigue. This happens because there is not enough oxygen which red blood cells carry throughout the body from the lungs. Other symptoms may include headaches, shortage of breath, paleness and chest pains. Sometimes, a specific sign of anemia may be jaundice or even arrhythmia and pains in the upper abdomen.

Some specific types of hemolytic anemia may have specific symptoms. For example, sickle cell anemia may be followed by leg pains since the abnormal sickle cells may clog small blood vessels and thus make the blood flow difficult. Alloimmune anemia may be followed by a serious condition which includes low blood pressure, fever and shock.

The diagnosis and treatment of hemolytic anemia

The best thing you should do if you suspect that you have some of the symptoms of hemolytic anemia is to consult your doctor. The diagnosis is set as a result of a number of test results, your family’s medical history and a physical exam. The tests include a complete blood count and other blood tests which are necessary in determining which type of hemolytic anemia is present and how serious it is. There also may be tests which help to determine the condition that is causing the anemia. These conditions may be some kind of deficiency, such as iron deficiency, kidney failure, lead poisoning etc. The treatment for hemolytic anemia includes medicines, blood transfusions, marrow and blood stem cell transplantations and even surgery. If the symptoms of the hemolytic anemia are mild, there might not even be any necessity for a treatment, but if the symptoms are serious and severe, the condition may even progress and have fatal consequences if it is left untreated. It is very important to follow the instructions and treatment given by the doctor since anemia may have serious consequences if it is not treated.

Other authority opinion: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001597/