What is Sickle Cell Disease?
Hi and welcome to this video about sickle cell disease! We’re going to look at an overview of the disease, the signs and symptoms, diagnosis, and management. Let’s get started!
Sickle cell disease is an inherited blood disorder resulting from the presence of a mutated form of hemoglobin—the sickle hemoglobin gene (HbS). Red blood cells become stiff, sticky, and oblong shaped, like a sickle. These sickle cells tend to cluster together on the lining of blood vessels, causing blockages and preventing adequate oxygen delivery to the tissues, which can cause pain, organ dysfunction, and complications. Sickle cell anemia is the most severe form of sickle cell disease.
Sickle cell disease (SCD) is chronic, debilitating, and sometimes fatal. SCD usually becomes evident in early childhood, but the signs and symptoms can vary considerably from person to person and change throughout their lifetime. Early symptoms seen in children include painful swelling of hands and feet, fussiness or fatigue from anemia, and jaundice. Most symptoms of sickle cell disease result from anemia and vaso-occlusive events resulting in tissue ischemia and infarction. Anemia is always present and usually severe, with typical hemoglobin values between 7 and 10 g/dL. Bone enlargement often occurs as a result of bone marrow expansion in childhood to compensate for anemia. Jaundice is also common, often seen in the sclera. Since SCD causes the obstruction of circulation by sickle-shaped RBCs, the result is decreased oxygen delivery to organs and subsequent pain. Patients describe the pain as sharp, stabbing, intense, or throbbing; often occurring in the lower back, legs, arms, abdomen, and/or chest. Painful sickle cell crisis causes severe pain in various parts of the body and may be accompanied by vomiting, fever, and dyspnea. The painful crises are sometimes precipitated by:
- viral infection
- temperature changes
or they may occur for no known reason. Complications of sickle cell include susceptibility to infection, stroke due to decreased oxygen supply, and renal failure as a result of reduced blood flow. Hepatosplenomegaly is common in children, but because of repeated infarctions, fibrosis results, and the spleen of adults is usually atrophied. Other common complications include cholelithiasis, cardiomegaly, dysrhythmias, and heart failure in adults.
Diagnosis of sickle cell disease varies with the age of the patient. Prenatal testing can be done by obtaining fetal DNA samples by chorionic villus sampling. Newborn screening is required nationwide at 24-72 hours of age for early recognition of affected infants. Despite newborn screening, many patients with SCD may still be undiagnosed. Patients with a family history of sickle cell disease or trait should be screened with a number of tests:
- A peripheral blood smear – identifies partially or completely sickled or crescent-shaped cells.
- Hemoglobin solubility testing – looks for the presence of abnormal Hemoglobin S in a blood sample, but it cannot differentiate between sickle cell trait and sickle cell anemia.
- Hemoglobin electrophoresis – identifies any abnormal hemoglobin types and differentiates between sickle cell trait and sickle cell disease.
- A CBC shows reticulocytosis, leukocytosis, decreased hemoglobin and RBCs, and elevated platelets.
- A serum bilirubin test would be elevated due to increased RBC hemolysis.
- ABGs – may reflect decreased PO2 or acidosis.
- Bone x-rays may indicate osteoporosis, osteosclerosis, osteomyelitis, or avascular necrosis.
Treatment for sickle cell disease includes regular health maintenance measures to help control symptoms as well as management of disease complications as they arise. Supportive therapy during a painful sickling episode includes IV hydration and a liberal amount of analgesics, usually opioids. IV morphine is safe and effective and NSAIDS are often used to reduce the opioid requirement, but they must be used cautiously in patients with renal disease. Patients with suspected bacterial infections or acute chest syndrome require broad-spectrum antibiotics right away, to avoid a sickle cell crisis. Chronic, or recurring, RBC transfusion therapy may be effective in preventing or managing complications from sickle cell anemia, including aplastic crises, cardiopulmonary signs or symptoms, and life-threatening events that would benefit from improved oxygen delivery. Transfusion is not helpful during an uncomplicated painful crisis. Pulmonary function is monitored and pulmonary hypertension is treated early if found. Incentive spirometry is used to prevent pulmonary complications, and bronchoscopy is done to identify the source of pulmonary disease. A peripheral blood stem cell transplant is the only curative treatment for sickle cell disease, but it is generally restricted to patients with advanced disease complications due to the risks associated with the therapy. Long-term management includes regular use of the medication hydroxyurea along with folate supplementation. Hydroxyurea reduces sickling, decreases painful crises by 50%, decreases acute chest syndrome, and decreases transfusion requirements. It does cause neutropenia and thrombocytopenia, and it is a teratogen, so it should not be given to females of child-bearing age. Other drugs that have recently become available include L-glutamine, crizanlizumab, and voxelotor. Other approaches to managing SCD pain include heat and cold application, acupuncture and acupressure, physical therapy, and transcutaneous electric nerve stimulation (TENS).
It is important to educate patients on long-term management of sickle cell disease. Choosing a healthy diet and taking a daily folate supplement will help bone marrow make new red blood cells. Drinking plenty of water throughout the day will help prevent dehydration which increases the risk of a sickle cell crisis. Avoiding smoking and extreme heat or cold will help reduce the risk of a sickle cell crisis. Exercising daily while monitored by a health care provider is important. Carefully using over-the-counter medications, such as NSAIDS, is essential because of the possible renal effects.
Now that we’ve learned about sickle cell disease, let’s go over a few questions for review.
1. An adult patient with sickle cell disease is likely to have a hemoglobin value of:
- Between 3 and 5 g/dL
- Between 5 and 7 g/dL
- Between 7 and 10 g/dL
- Between 10 and 12 g/dL
2. During a patient assessment, the nurse notes that the patient’s face and skull bones are enlarged. He knows this is a compensatory response to:
3. Sickle-shaped red blood cells cause:
- Blockages in small vessels
- Decreased oxygen delivery to tissues
- Organ dysfunction
- All of the above
That’s all for now! Thanks for watching and happy studying!