Hemoglobin is the main substance of red blood cells, and its function is to help red blood cells carry oxygen from the air in our lungs to all parts of the human body. Normal red blood cells contain a hemoglobin called “hemoglobin A”. Hemoglobin S (S is for sickle) and hemoglobin C are abnormal types of hemoglobins. Normal red blood cells in the human body are soft, round, and can squeeze through tiny blood vessels. Normally, red blood cells live for around one hundred and twenty days before new ones are formed to replace them.
Individuals with sickle cell conditions produce a different form of the hemoglobin A, called hemoglobin S (S is for sickle). The red blood cells containing hemoglobin S do not live as long as normal red blood cells (which is normally about days), and they also become stiff and distorted in shape, and they have difficulty passing through the body’s small blood vessels. When a sickle cell blocks small blood vessels, less blood is able reach that particular part of the body, and then the tissue that does not receive a normal blood flow eventually will become damaged. This process is what causes the variety of complications of sickle cell disease.
There are several different types of sickle cell disease, but the most common are: Sickle Cell Anemia (SS), Sickle-Hemoglobin C Disease (SC)Sickle Beta-Plus Thalassemia and Sickle Beta-Zero Thalassemia.
The Sickle Cell trait (AS) is an inherited condition in which both hemoglobin A and S are produced in the red blood cells, and there are always more A hemoglobin than S hemoglobin. Sickle cell trait itself is not a type of sickle cell disease. In general, people with sickle cell trait are healthy individuals.
The variety of sickle cell conditions are in fact inherited from parents in much the same way as one will inherit blood type, hair color and hair texture, eye color and all other physical traits. The types of hemoglobin an individual makes in the red blood cells depends upon what hemoglobin genes the individual inherits from his or her parents. Hemoglobin genes are like most genes in that hemoglobin genes are inherited in two sets (one from each parent).
A simple an painless blood exam that is followed by a laboratory technique called Hemoglobin Electrophoresis will determine the type of hemoglobin an individual has. When a person passes an electric charge through a solution of hemoglobin, distinct hemoglobins move different distinct distances, depending on the hemoglobin composition. This technique of diagnosis differentiates between normal hemoglobin (A), Sickle hemoglobin (S), and other different kinds of hemoglobin (such as C, D, E, and others.).
Sickle cells are destroyed rapidly in the body of individuals with sickle cell disease, causing jaundice, anemia, and the formation of gallstones.
The sickle cells also will block the flow of blood through the body’s vessels, which results in lung tissue damage (acute chest syndrome), episodes of pain (in the arms, legs, chest and abdomen), as well as stroke and priapism (condition of a painful and prolonged erection). The blockage may also cause damage to the organs, including the kidneys, spleen, and liver. Spleen damage makes sickle cell disease patients, and particularly young children, easily vulnerable to certain bacterial infections.
For patients with sickle cell disease, health maintenance entails early diagnosis, preferably in the newborn period and includes a prophylaxis of penicillin as well as vaccinations against pneumococcus bacteria, and also would include folic acid supplementation.
Treatment of complications of sickle cell disease will often include pain management, antibiotics, intravenous fluids to maintain hydration, blood transfusion, and surgery along with a system of psycho social support. Like all patients with chronic disease, patients with sickle cell disease are best managed in a comprehensive multi-disciplinary course of treatment.
Blood transfusions may help and be to the benefit of sickle cell disease patients by reducing recurrent crises of pain, reduce the risk of stroke as well as other complications. Because the red blood cells contain iron, and there is no natural way for the body to eliminate iron, sickle cell patients who receive repeated blood transfusions can accumulate iron in the body until the level of iron reaches toxic concentrations. It is important to for treatment, to remove excess iron from the body, because the iron might gather in the liver, the heart, and other organs, and may lead to organ damage. Iron overload treatments are available for this problem.
In the search for a substance that might prevent red blood cells from “sickling” but without causing harm to other parts of the body, the substance Hydroxyurea was found to reduce frequency of severe pain episodes, acute chest syndrome as well as the need for blood transfusions in adult individuals with sickle cell disease. Droxia, which is the prescription form of hydroxyurea, was approved by the FDA in 1998 and is currently available for adult individuals with sickle cell anemia. Studies are now underway to determine the proper hydroxyurea dosage for use in children.
Other treatment options that are in clinical development include new, and more convenient options than the current therapies used now to eliminate iron overload that is caused by repeated blood transfusions.