Long Way Education

By Fatma Sobih

Fatma is a pharmacist. She is interested in searching for and writing about diseases.

This article covers:

1. The pathophysiology of sickle cell anemia
2. Causes
3. Diagnostic tests
4. Treatment
5. Manifestations
6. Disease complications
7. Prevention Tips

Sickle Cell Anemia

Sickle cell anemia is a group of disorders known as sickle cell disease and is usually inherited from a person’s parents.

Sickle cell anemia is an inherited disorder of red blood cells in which not enough healthy red blood cells circulate oxygen to the body, contained in the hemoglobin protein.

It results in a rigid, sickle-like shape under certain conditions. Sickle cell anemia problems usually start between the ages of 5 and 6 months. Usually, elastic, round red blood cells move easily through blood vessels. Sickle cell anemia causes the red blood cells to be shaped like a sickle or a half-moon. These viscous cells can get attached to small blood vessels, which may slow or block the inflow of blood and oxygen to parts of the body.

Individuals who have sickle cell disease are susceptible to threatening infections, excruciating pain episodes, and other health issues that can harm any organ in the body.

Many healthcare organizations have expressed interest in sickle cell disease. For example, the National Institute for Children’s Health Quality has joined the Health Resources and Services Administration (HRSA) in recognizing World Sickle Cell Day.

Pathophysiology

Red blood cells are characterized by their biconcave shape and their ability to deform as they pass through capillaries.

Did You Know?

The pathophysiology of sickle cell anemia is primarily caused by a loss of flexibility.

This starts due to a single-point gene mutation that causes the polymerization of mutant hemoglobin S, thus affecting the flow and survival of the red blood cells. This polymerization occurs when the hemoglobin S is deoxygenated, causing a defect in the shape of the erythrocyte. Continued deoxygenation of red cells gives them a sickle shape, which damages the plasma membranes. As a result, erythrocytes are unable to smoothly deform and pass through capillaries. This usually leads to conditions such as ischemia and vaso-occlusive crises.

Causes of Sickle Cell Anemia

Sickle cell disease is a genetic disease transmitted by receiving two sickle cell genes, one from each parent. A normal, healthy red blood cell contains four chains of hemoglobin A: two β-globin chains and two alpha-globin chains. However, sickle cell anemia results in at least one subunit of beta-globin being replaced by hemoglobin S.

Hemoglobin S makes the red blood cell stiff and gradually distorts its shape, making it sickle-shaped. The patient’s body destroys sickle-shaped cells. Thus, the patient is diagnosed with anemia. The probability distribution of sickle cell anemia depends on which parent is a carrier of the disorder.

If both parents are carriers of the defective gene, then there is a 25% probability that the child will be diseased. On the other hand, if only one parent is a carrier, then there would be a 50% chance of the child being diseased.

Diagnostic Tests

• In adults, a vein sample can be used to detect sickle cell anemia through several tests.
• In the case of young children, the blood sample is taken from a finger or heel.
• Other tests may be done before birth by taking a sample of the fluid surrounding the baby (amniotic fluid).

Treatment

Nowadays, many treatments are available that reduce the complications of the disease:

• Hydroxyurea is a medicine that can decrease several complications of sickle cell anemia, such as neurological and vision problems. On the other hand, taking hydroxyurea may result in serious infections or bleeding. Important note: (Do not use this medicine without consulting your doctor or pharmacist.)
• A stem cell transplant can be applied; however, it needs a donor who has compatible bone marrow, and this procedure is done by infusing healthy cells into the bone marrow (the site of red blood cell production). The transplant can have some side effects, such as an accidental illness that is life-threatening or even fatal.

Manifestation

In most cases, symptoms appear after six months. In these months, fetal hemoglobin, or hemoglobin F, is high in the blood. When it decreases, patients usually apply to the pediatric service with what we call “hand and foot” syndrome. We can roughly divide the sudden onset of disease symptoms into long-term side effects.

Complications of Sickle Cell Disease

The complications of sickle cell disease include:

1. Acute Pain Crisis: Also known as sickle cell or vaso-occlusive crisis, this can happen without warning when sickle cells block blood flow. People describe this pain as razor-sharp, enormous, stabbing, or throbbing. Pain can strike almost anywhere in the body and in more than one spot at a time. Common areas affected by pain include the abdomen, chest, lower back, arms, and legs. A crisis can be caused by high altitude, dehydration, disease, stress, or temperature changes. Often, the person does not know what is causing the crisis.
2. Liver Problems: Sickle cell intrahepatic cholestasis is an uncommon but severe type of liver damage that happens when sickled red cells block blood vessels in the liver. This blockage prevents enough oxygen from reaching liver tissue. These episodes are usually sudden and may happen more than once. Children often recover, but some adults may have chronic problems that lead to liver failure. Frequent blood transfusions can lead to liver damage from iron overload.
3. Eye: Neovascularization (new vessel formation) and arteriovenous aneurysm occur with the occlusion of retinal vessels. As a result, bleeding, scarring, retinal detachment, and blindness may occur. Retinal changes may not be fully assessed initially with an ophthalmoscope.
4. Leg Sores: Leg ulcers occur spontaneously due to minor trauma around the inner or outer heel.
5. Kidney: Patients with sickle cell disease can experience simple disorders or severe conditions. The most characteristic feature of sickle cell patients is the urine concentration defect. Painless blood cells can be seen in the urine of 50% of patients with sickle cell nephropathy. Sickle cell crises, heat deficiency, lack of oxygen, and use of non-steroidal anti-inflammatory drugs can cause kidney cell death. Recurrent urinary infections may be a risk factor.
6. Acute Pain Crisis: Known as sickle cell or vaso-occlusive crisis, this can happen without warning when sickle cells block blood flow. People describe this pain as razor-sharp, enormous, stabbing, or throbbing. Pain can strike almost anywhere in the body and in more than one spot at a time. Common areas affected by pain include the abdomen, chest, lower back, arms, and legs. A crisis can be caused by high altitudes, dehydration, disease, stress, or temperature changes. Often, a person does not know why the crisis occurred.

Prevention Tips

To prevent or decrease sickle cell anemia, please keep in mind the following points:

1. Avoid locations or circumstances that expose you to high altitudes, such as going on mountain hikes or visiting high-altitude cities.
2. Steer clear of locations or circumstances that expose you to low oxygen levels, such as extremely demanding exercise.
3. Since bacteria can be dangerous to children with sickle cell disease, it is important to cook food safely.

References

• Sickle cell anemia.
• About Sickle Cell Disease
• Sickle cell disease: renal manifestations and mechanisms.
• Leg ulcers: atypical presentations and associated comorbidities.
• About Sickle Cell Disease.
• SICKLE CELL DISEASE Symptoms.
• What is sickle cell disease?
• Complications of Sickle Cell Disease.
• Pathophysiology of Sickle Cell Disease.
• The Switch from Fetal to Adult Hemoglobin.

©Fatma Mohammad Sobih, 2023

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