Blood consists of a liquid and protein component called serum, and a cellular component that is largely made up of red blood cells. These cells carry oxygen to the tissues and help balance the acidity of the blood. Low red blood cell counts are called anemia and have numerous causes. Sickle cell anemia is caused by a genetic mutation. The condition is called "sickle cell" because the cells become elongated and crescent shaped. This condition should be managed by a licensed health care professional.
Mechanism
Genes are long chemical codes inside cells that serve as blueprints for the cell to make proteins. Proteins are made of smaller chemicals called amino acids. Hemoglobin is the main protein in red blood cells; it is the protein that carries oxygen. In sickle cell anemia, a gene for hemoglobin is mutated so that one amino acid in hemoglobin, glutamate, is substituted for another, valine. Glutamate and valine have very different properties. The result is that when hemoglobin is exposed to lower oxygen levels, the hemoglobin proteins aggregate together. This forms large structures inside the red blood cells that distort and damage the cells.
Symptoms and Signs
People with sickle cell anemia suffer from recurring painful episodes called sickle cell crisis. The crisis last from hours to days and can affect any part of the body. Chest, abdominal, finger, toe and bone pain are common. Other problems include delayed growth, spleen damage, fever, fatigue, paleness, painful prolonged erections, excessive thirst and urination, ulcers and jaundice. These symptoms are due a decreased capacity of blood to carry oxygen in the damaged red cells and cells becoming trapped in and occluding blood vessels.
Diagnosis
A number of tests can indicate sickle cell disease. Blood smears visualized under a microscope can show sickled red blood cells. Hemoglobin electrophoresis is a procedure in which an electrical current is used to pull hemoglobin through a gel. Affected hemoglobin will move at a different rate than normal hemoglobin. Genetic tests are also available.
Complications
Complications of sickle cell anemia include priapism, a painful erection that will not go away without intervention and damage to other tissues such as lung, kidneys and liver. Other common complications include gallstones, spleen failure, infections and drug addiction. Further complications involve nerve damage causing vision impairment, strokes and even death.
Treatment
Treatment depends on the complications. For example, pain episodes are generally treated with IV fluids and powerful pain medications. Infections will require antibiotic treatment. Hydroxyurea is sometimes used to treat attacks or decrease the number of painful episodes. Prevention may involve avoiding strenuous activity, high altitudes with low oxygen and smoking. Keeping well hydrated is also recommended.
References
- "Lehninger Principles of Biochemistry"; David L. Nelson and Michael M. Cox; 4th Ed 2004
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al.; 17th Ed 2008
