Sickle cell disease: Clinical sciences

Sickle cell disease, or SCD for short, is a genetic disorder affecting hemoglobin that causes red blood cells to become deformed and sickle-shaped. Sickled cells can obstruct small blood vessels and disrupt the supply of oxygen to tissues, resulting in severe pain and tissue damage within any organ system. Once the diagnosis of SCD is confirmed, patients should be monitored for related complications.

Now, if your patient presents with a chief concern suggesting SCD, you should first perform an ABCDE assessment to determine if your patient is unstable or stable. If unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access, start IV fluids, and put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry. Finally, if needed, provide supplemental oxygen.

Now, here’s a clinical pearl! Severe complications of SCD include acute chest syndrome and acute episodes of vaso-occlusion and hemolysis that present with life-threatening ischemia or infarction of the central nervous system or pulmonary vasculature. Be on the lookout for the sudden development of red-flag signs such as new-onset weakness, altered mental status, chest pain, or respiratory distress.

Now, let’s go back to the ABCDE assessment and take a look at stable patients.

First, obtain a focused history and physical examination. Your patient might report weakness and fatigue, as well as a history of chronic anemia and recurrent infections. Additionally, the family history may be significant for other relatives with SCD. Patients often experience acute or chronic pain, especially in the long bones, pelvis, or back.

On the other hand, a physical exam typically reveals an ill-appearing patient with tachycardia and an audible heart murmur on cardiac auscultation. Skin exam commonly reveals jaundice and pallor, and you might also notice scleral icterus. Finally, you might find bone and joint tenderness, warmth, or swelling.

At this point, you should suspect SCD, so order labs, including a CBC with a peripheral smear, a reticulocyte count, CMP, haptoglobin, and hemoglobin electrophoresis.

Now, let’s take a look at the lab results.

The CBC will demonstrate low hemoglobin and hematocrit, and the peripheral smear will reveal sickle-shaped cells. There might be an elevated reticulocyte count, increased levels of indirect bilirubin, and high lactate dehydrogenase; while haptoglobin will be low, as these patients are actively hemolyzing. Hemoglobin electrophoresis will reveal the presence of Hemoglobin S as well as absent or decreased Hemoglobin A levels. Based on these lab results, you can diagnose sickle cell disease.

Now, here’s another clinical pearl to keep in mind! All newborns in the US are screened for SCD. In other words, most SCD diagnoses are established in early infancy. Infants with SCD are at increased risk of infection from encapsulated organisms, such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, so, in addition to routine childhood immunizations, they should receive prophylactic penicillin until 5 years of age.

Ok, now once you diagnose SCD, begin the initial steps of medical management. Patients with SCD commonly present with acute vaso-occlusive episodes, also known as pain crises, so it’s important to administer pain medication promptly. If the pain isn’t severe you can start with NSAIDs. But, keep in mind that patients often require intravenous opioids for effective pain control, so consider patient-controlled analgesia for hospitalized patients. Additionally, start IV fluids to ensure adequate hydration and reduce blood viscosity. Finally, if anemia is severe and symptomatic, give a transfusion of packed red blood cells. Transfusions are beneficial acutely, for severe symptomatic anemia, as well as prophylactically, for stroke prevention. However, frequent transfusions can lead to alloimmunization and iron overload, so be cautious when deciding whether to transfuse your patient.

Alright, now that you’ve provided initial treatment, it’s time to focus on chronic medical management. This includes medications like hydroxyurea, which increases fetal hemoglobin production and reduces cell sickling, as well as folic acid, which is essential for adequate red blood cell production. Individuals with sickle cell disease are at increased risk of infection, so make sure your patient is up to date on immunizations, especially those that protect against infections with encapsulated organisms like Streptococcus pneumoniae. Finally, encourage genetic counseling for all first-degree relatives, in order to discuss inheritance of SCD as well as the risk of transmission to future children.

Alright, now once you initiate the management, make sure to assess your patient for complications related to SCD.

First, let’s start with a stroke! These patients could present with a headache or neurological symptoms, like unilateral weakness or speech difficulties, and the physical exam demonstrates focal neurological deficits like hemiparesis. In this case, order a CT of the head, and if findings suggest ischemia or infarction, diagnose stroke.

Next, let’s take a look at acute chest syndrome!

These individuals might present with fever, cough with or without sputum production, shortness of breath, and chest pain. Physical examination may reveal an elevated temperature and hypoxia, with decreased breath sounds and crackles on auscultation. Next, order a chest X-ray, and if it shows pulmonary infiltrates, atelectasis, cardiomegaly, or effusion, diagnose acute chest syndrome.