What is sickle cell disease? Who is at risk for this disease? What is the pathophysiology behind it?
These are some of the questions I hope to answer with this article. Hemoglobin disorders can be somewhat confusing to understand. By taking an in-depth look at this disease process, it is my hope that it will make more sense to you – which in turn will allow you to be able to more effectively educate your patients.
So let’s get started!!
Before we can understand the disease itself, we need to review some basics about the hemoglobin molecule. First, normal hemoglobin has four polypeptide chains. The alpha chains are “encoded” by 2 separate genes on chromosome 16 and the beta chains are “encoded” by a gene on the 11th chromosome.
So, a normal hemoglobin has 2 beta genes and 2 alpha genes. Combining each of these globin chains with a heme group allows the molecule (hemoglobin) to bind with iron and oxygen thus, aiding in oxygen transportation throughout the body.
So with that information, you can then build on it to understand sickle cell. Normally, our erythrocytes are very flexible, which is important for circulation. In sickle cell anemia, a defect occurs along the beta chains of hemoglobin. Because of this autosomal recessive single gene defect, the shape of the erythrocytes changes from a round to a crescent shape.
Why would this be a problem??
With the change in shape of the hemoglobin molecule, it becomes less flexible – if less flexible, it cannot effectively bend and flex to maneuver through the small vessels. So, this results in a decrease/lack of oxygen available to specific tissues because the sickled cell becomes obstructed within the capillary. Additionally, this may cause the hemoglobin to break… If a lack of oxygen is prolonged, infarction may occur.
If early destruction of the sickled erythrocytes occurs, then there is a decrease in the amount of hemoglobin present in the blood, which can lead to anemia. Additionally, spleenomegaly, bacterial infections (specifically pneumonia due to the decrease in immune function from chronic spleenomegaly), and spleen destruction are possible.
Other complications may include, but are not limited to, stroke, leg ulcers, avascular necrosis of the hip or shoulder, and other cardiac manifestations. So, as you can see, this is of big concern. This disease is more notably present in African American’s than in Caucasians. The overall treatment goals include fluid replacement to help correct any volume depletion noted during a crisis, pain management, and symptom control.
I am attaching citations to a couple of reference journals that may be helpful for more detail regarding treatment and management if interested. The pathophysiology book is really helpful and does a great job at explaining diseases in a short, sweet, and concise manner.
Yawn, B., John-Sowah, J., (2015). Management of sickle cell disease: Recommendations from the 2014 expert panel report. American Family Physician. 92(12). 1069-1076.
Berkowitz, A. Clinical Pathophysiology Made Ridiculously Simple. Miami, Florida:MedMaster.
Tracy Lindstrom RN, BSN, DNP-s