An 18-month-old boy is brought to the emergency department by his adoptive mother due to increasing irritability. The patient has been tiring easily for the past 3-4 days; now he is irritable, constantly crying, and inconsolable. The mother tried to comfort him by playing with his toys, but he refuses to pick them up and cries more when he attempts to walk. The patient has had no recent trauma, fever, cough, or runny nose. He was adopted 6 months ago from Nigeria and has been healthy. Immunizations are up to date. Family history is unknown. Temperature is 37.8 C (100 F) and pulse is 120/min. The patient is alert and appears uncomfortable. Pupils are equal and reactive. Scleral icterus is present and the conjunctivae are pale. Cardiopulmonary examination is normal. The hands and feet are mildly swollen and tender to palpation. Hemoglobin is 9 g/dL. Which of the following tests would establish the underlying diagnosis in this patient?

Question

An 18-month-old boy is brought to the emergency department by his adoptive mother due to increasing irritability.  The patient has been tiring easily for the past 3-4 days; now he is irritable, constantly crying, and inconsolable.  The mother tried to comfort him by playing with his toys, but he refuses to pick them up and cries more when he attempts to walk.  The patient has had no recent trauma, fever, cough, or runny nose.  He was adopted 6 months ago from Nigeria and has been healthy.  Immunizations are up to date.  Family history is unknown.  Temperature is 37.8 C (100 F) and pulse is 120/min.  The patient is alert and appears uncomfortable.  Pupils are equal and reactive.  Scleral icterus is present and the conjunctivae are pale.  Cardiopulmonary examination is normal.  The hands and feet are mildly swollen and tender to palpation.  Hemoglobin is 9 g/dL.  Which of the following tests would establish the underlying diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bf7e_79cb_8f63_39b14ea7baac_MD0005_00 Sickle cell disease (SCD) is an autosomal recessive disorder caused by a hemoglobin (Hb) beta globin chain mutation. When patients are exposed to triggers (eg, cold weather, dehydration, overexertion), the red blood cells (RBCs) sickle and destroy erythrocytes. In children age <4, a common sequestration site is the small bones of the hands and feet; this sequestering results in bone infarction and a vaso-occlusive pain crisis known as dactylitis (painful swelling of the hands or feet). Because of systemic inflammation, patients often have an associated low-grade fever. RBC destruction due to intravascular hemolysis also results in chronic hemolytic anemia (eg, scleral icterus, jaundice). The gold standard for diagnosing SCD is hemoglobin electrophoresis, which shows predominant HbS with absent HbA. Acute management includes hydration and pain control; hydroxyurea can help prevent future vaso-occlusive episodes. (Choice A) A direct Coombs test is positive in autoimmune hemolytic anemia, which can be associated with systemic lupus erythematosus. Patients with lupus have joint pain; however, this patient does not fulfill diagnostic criteria (eg, malar rash, oral ulcers). (Choice B) Glucose-6-phosphate dehydrogenase deficiency typically presents shortly after exposure to an oxidative stress (eg, sulfa drugs, fava beans) with hemolysis (eg, jaundice, pallor, dark urine). Patients may have associated abdominal and/or back pain rather than joint pain. (Choice D) Parvovirus may cause anemia and arthropathy; however, the anemia is due to red cell aplasia rather than hemolysis. Arthritis is more common in adolescents/adults than in young children. (Choice E) Thick and thin smears are used to diagnose malaria, which causes anemia from hemolysis of parasitized RBCs. Cyclical high fever and malaise, headache, and abdominal pain are typical, but are not seen in this patient. Educational objective: Early manifestations of sickle cell disease include dactylitis, painful swelling of the hands or feet due to bone infarction, and hemolytic anemia. Predominant hemoglobin S with absent hemoglobin A on hemoglobin electrophoresis is diagnostic. References: Musculoskeletal manifestation of sickle cell disease: a review. (http://www.ncbi.nlm.nih.gov/pubmed/26623213) Sickle cell disease. (http://www.ncbi.nlm.nih.gov/pubmed/27637966)

An 18-Month-Old Boy Is Brought to the Emergency Department by His