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Sickle cell disease Johanna L. Chelcun, MHS, PA-C
GENERAL FEATURES • Autosomal recessive inherited hemoglobinopathy affecting the beta-globin genes on chromosome 11 • Homozygous sickle cell disease is characterized by the genotype HbSS; heterozygous sickle cell trait is characterized by the genotype HbAS. • HbSS disease leads to chronic, intrinsic hemolytic anemia due to sickling of red blood cells (RBCs) in hypoxemic or acidotic states. • Acute splenic sequestration of RBCs can lead to acute decreases in hemoglobin, hypovolemia, hypoxia, and potentially death. • Vaso-occlusion by sickled RBCs leads to pain, tissue ischemia, and necrosis. • Increased risk of infection including pneumonia, meningitis, osteomyelitis, and sepsis • Other potential complications include stroke, retinopathy, acute chest syndrome, pulmonary hypertension, cholelithiasis, splenic infarction, renal disease, priapism, and avascular necrosis. CLINICAL ASSESSMENT • Assessing family history is key to diagnosis. • Patients often are asymptomatic in infancy due to the presence of fetal hemoglobin (HbF). • Dactylitis commonly is the first clinical manifestation of disease. • Symptoms of vaso-occlusive crisis include severe musculoskeletal, abdominal, and/or back pain. Fever or priapism may be present. • Physical findings include systolic murmur, hepatosplenomegaly, jaundice or pallor, and delayed growth. • Acute chest syndrome presents with hypoxia, fever, tachycardia, and abnormal lung sounds. DIAGNOSIS • Usually made by newborn screening using hemoglobin electrophoresis: ¡ Sickle cell disease—80% to 100% HbS, no HbA1 ¡ Sickle cell trait—30% to 45% HbS, 50% to 70% HbA1 Johanna L. Chelcun is a clinical assistant professor in the PA program at Quinnipiac University in Hamden, Conn. The author has indicated no relationships to disclose relating to the content of this article. Dawn Colomb-Lippa, MHS, PA-C, and Amy M. Klingler, MS, PA-C, department editors DOI: 10.1097/01.JAA.0000438537.22634.0a Copyright © 2014 American Academy of Physician Assistants
• Sickle cell disease manifests as chronic hemolytic anemia with normal to high mean corpuscular volume, reticulocytosis, and leukocytosis. Serum haptoglobin is low or absent, with elevated bilirubin and lactate dehydrogenase. • Sickled RBCs, target cells, and Howell-Jolly bodies on peripheral blood smear in sickle cell disease • Additional evaluation depends on clinical picture: ¡ Chest radiograph reveals pulmonary infiltrate(s) in acute chest syndrome. ¡ MRI or bone scan if osteomyelitis is suspected ¡ Brain imaging to evaluate for stroke in patients with neurologic symptoms ¡ Patients presenting with fever should be thoroughly evaluated for infection, including blood cultures. TREATMENT OF SICKLE CELL DISEASE • Once the diagnosis is established, closely manage the patient with regular screenings: ¡ Complete blood cell (CBC) count, reticulocyte count, renal and liver function tests, urinalysis ¡ Pulmonary function tests ¡ Neuropsychologic testing
QUESTIONS 1. A 10-year-old boy with sickle cell disease and his parents present to your office to establish care after recently moving to town. Which of the following would not be part of your initial laboratory evaluation? a. CBC count b. blood culture c. reticulocyte count d. renal function tests 2. When counseling the patient and family about the complications and course of sickle cell disease, which of the following should be included in your guidance? a. Priapism is common and will always resolve spontaneously with conservative management at home. b. A fever does not warrant medical evaluation unless the fever is very high or lasts longer than 3 days. c. The patient should receive annual pneumococcal and influenza vaccinations. d. The patient may participate in all activities without limitations.
JAAPA Journal of the American Academy of Physician Assistants
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
www.JAAPA.com
45
QUICK RECERTIFICATION SERIES
•
•
• •
• •
•
• Antibiotic prophylaxis against Streptococcus pneumoniae sepsis with oral penicillin, 125 to 250 mg twice daily in children until age 5 years • Immunizations against pneumococcus and influenza, in addition to routine childhood vaccinations • Address psychosocial issues, including delayed growth and puberty, activity limitations (avoidance of dehydration, cold temperatures, smoking, alcohol, and drug use), contraception and family planning, effect of chronic disease, and awareness of decreased life span • Genetic counseling for all patients with sickle cell disease and sickle cell trait • Hematopoietic stem cell transplantation may be considered in patients with significant complications, but is not frequently used due to associated risks.
Answers
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1. B. Blood cultures should be obtained in patients with sickle cell disease who present with fever or other signs of infection, which is not the case with this patient. Routine laboratory tests include a CBC count, reticulocyte count, and renal and liver function tests. 2. C. In addition to routine childhood vaccinations, patients with sickle cell disease should be immunized against pneumococcus and seasonal influenza.
Annual transcranial Doppler starting at age 2 years Fundoscopic examinations ¡ Echocardiogram Prevention of pain crises with hydration. Patients should avoid smoking and high altitudes, and should rest intermittently to reduce the risk of hypoxia during strenuous activity or sports. Treatment of pain crises includes supplemental oxygen, fluids, and analgesics (nonsteroidal anti-inflammatory drugs, acetaminophen, or opioids). Severe pain requiring hospitalization can be treated with parenteral analgesics or patient-controlled analgesia. Broad-spectrum antimicrobial drugs are indicated in patients with signs of infection. Acute chest syndrome is treated with oxygen, incentive spirometry, and antibacterials which also offer coverage for atypical organisms. Urology consultation for prolonged priapism that does not respond to hydration and analgesics Hydroxyurea increases HbF production and may be used in some patients to reduce the severity and frequency of pain episodes and acute chest syndrome. Blood transfusions may be used in select patients with acute chest syndrome, splenic sequestration, aplastic crisis, abnormal transcranial Doppler studies, and before surgical procedures. Patients receiving chronic transfusions may require iron chelation therapy to prevent hemosiderosis. ¡
Visit www.jaapa.com Choose the Article Collections tab and click on Quick Recertification Series.
46
www.JAAPA.com
Volume 27 • Number 1 • January 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Sickle cell disease Johanna L. Chelcun, MHS, PA-C
GENERAL FEATURES • Autosomal recessive inherited hemoglobinopathy affecting the beta-globin genes on chromosome 11 • Homozygous sickle cell disease is characterized by the genotype HbSS; heterozygous sickle cell trait is characterized by the genotype HbAS. • HbSS disease leads to chronic, intrinsic hemolytic anemia due to sickling of red blood cells (RBCs) in hypoxemic or acidotic states. • Acute splenic sequestration of RBCs can lead to acute decreases in hemoglobin, hypovolemia, hypoxia, and potentially death. • Vaso-occlusion by sickled RBCs leads to pain, tissue ischemia, and necrosis. • Increased risk of infection including pneumonia, meningitis, osteomyelitis, and sepsis • Other potential complications include stroke, retinopathy, acute chest syndrome, pulmonary hypertension, cholelithiasis, splenic infarction, renal disease, priapism, and avascular necrosis. CLINICAL ASSESSMENT • Assessing family history is key to diagnosis. • Patients often are asymptomatic in infancy due to the presence of fetal hemoglobin (HbF). • Dactylitis commonly is the first clinical manifestation of disease. • Symptoms of vaso-occlusive crisis include severe musculoskeletal, abdominal, and/or back pain. Fever or priapism may be present. • Physical findings include systolic murmur, hepatosplenomegaly, jaundice or pallor, and delayed growth. • Acute chest syndrome presents with hypoxia, fever, tachycardia, and abnormal lung sounds. DIAGNOSIS • Usually made by newborn screening using hemoglobin electrophoresis: ¡ Sickle cell disease—80% to 100% HbS, no HbA1 ¡ Sickle cell trait—30% to 45% HbS, 50% to 70% HbA1 Johanna L. Chelcun is a clinical assistant professor in the PA program at Quinnipiac University in Hamden, Conn. The author has indicated no relationships to disclose relating to the content of this article. Dawn Colomb-Lippa, MHS, PA-C, and Amy M. Klingler, MS, PA-C, department editors DOI: 10.1097/01.JAA.0000438537.22634.0a Copyright © 2014 American Academy of Physician Assistants
• Sickle cell disease manifests as chronic hemolytic anemia with normal to high mean corpuscular volume, reticulocytosis, and leukocytosis. Serum haptoglobin is low or absent, with elevated bilirubin and lactate dehydrogenase. • Sickled RBCs, target cells, and Howell-Jolly bodies on peripheral blood smear in sickle cell disease • Additional evaluation depends on clinical picture: ¡ Chest radiograph reveals pulmonary infiltrate(s) in acute chest syndrome. ¡ MRI or bone scan if osteomyelitis is suspected ¡ Brain imaging to evaluate for stroke in patients with neurologic symptoms ¡ Patients presenting with fever should be thoroughly evaluated for infection, including blood cultures. TREATMENT OF SICKLE CELL DISEASE • Once the diagnosis is established, closely manage the patient with regular screenings: ¡ Complete blood cell (CBC) count, reticulocyte count, renal and liver function tests, urinalysis ¡ Pulmonary function tests ¡ Neuropsychologic testing
QUESTIONS 1. A 10-year-old boy with sickle cell disease and his parents present to your office to establish care after recently moving to town. Which of the following would not be part of your initial laboratory evaluation? a. CBC count b. blood culture c. reticulocyte count d. renal function tests 2. When counseling the patient and family about the complications and course of sickle cell disease, which of the following should be included in your guidance? a. Priapism is common and will always resolve spontaneously with conservative management at home. b. A fever does not warrant medical evaluation unless the fever is very high or lasts longer than 3 days. c. The patient should receive annual pneumococcal and influenza vaccinations. d. The patient may participate in all activities without limitations.
JAAPA Journal of the American Academy of Physician Assistants
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
www.JAAPA.com
45
QUICK RECERTIFICATION SERIES
•
•
• •
• •
•
• Antibiotic prophylaxis against Streptococcus pneumoniae sepsis with oral penicillin, 125 to 250 mg twice daily in children until age 5 years • Immunizations against pneumococcus and influenza, in addition to routine childhood vaccinations • Address psychosocial issues, including delayed growth and puberty, activity limitations (avoidance of dehydration, cold temperatures, smoking, alcohol, and drug use), contraception and family planning, effect of chronic disease, and awareness of decreased life span • Genetic counseling for all patients with sickle cell disease and sickle cell trait • Hematopoietic stem cell transplantation may be considered in patients with significant complications, but is not frequently used due to associated risks.
Answers
¡
1. B. Blood cultures should be obtained in patients with sickle cell disease who present with fever or other signs of infection, which is not the case with this patient. Routine laboratory tests include a CBC count, reticulocyte count, and renal and liver function tests. 2. C. In addition to routine childhood vaccinations, patients with sickle cell disease should be immunized against pneumococcus and seasonal influenza.
Annual transcranial Doppler starting at age 2 years Fundoscopic examinations ¡ Echocardiogram Prevention of pain crises with hydration. Patients should avoid smoking and high altitudes, and should rest intermittently to reduce the risk of hypoxia during strenuous activity or sports. Treatment of pain crises includes supplemental oxygen, fluids, and analgesics (nonsteroidal anti-inflammatory drugs, acetaminophen, or opioids). Severe pain requiring hospitalization can be treated with parenteral analgesics or patient-controlled analgesia. Broad-spectrum antimicrobial drugs are indicated in patients with signs of infection. Acute chest syndrome is treated with oxygen, incentive spirometry, and antibacterials which also offer coverage for atypical organisms. Urology consultation for prolonged priapism that does not respond to hydration and analgesics Hydroxyurea increases HbF production and may be used in some patients to reduce the severity and frequency of pain episodes and acute chest syndrome. Blood transfusions may be used in select patients with acute chest syndrome, splenic sequestration, aplastic crisis, abnormal transcranial Doppler studies, and before surgical procedures. Patients receiving chronic transfusions may require iron chelation therapy to prevent hemosiderosis. ¡
Visit www.jaapa.com Choose the Article Collections tab and click on Quick Recertification Series.
46
www.JAAPA.com
Volume 27 • Number 1 • January 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
