A 1-year-old African American boy is brought to the emergency department by his parents with a 3-hour history of severe swelling and tenderness of the hands and feet. They do not know what caused the swelling and say that the boy cries when his hands or feet are touched. The patient has no history of recent illness and is up to date on all immunizations. The boy attends day care, but his parents are unsure about any sick contacts. His family history is significant for an older brother who died of pneumococcal sepsis at age 6. Physical examination shows bilateral, severe swelling of the hands and feet. Which of the following is most likely abnormal in this patient?

Question

A 1-year-old African American boy is brought to the emergency department by his parents with a 3-hour history of severe swelling and tenderness of the hands and feet.  They do not know what caused the swelling and say that the boy cries when his hands or feet are touched.  The patient has no history of recent illness and is up to date on all immunizations.  The boy attends day care, but his parents are unsure about any sick contacts.  His family history is significant for an older brother who died of pneumococcal sepsis at age 6.  Physical examination shows bilateral, severe swelling of the hands and feet.  Which of the following is most likely abnormal in this patient?

Quizplus · Accepted Answer

Sickle cell disease (SCD) is the most common autosomal recessive disorder in African Americans. Its manifestations include the following: Hemolysis: Repeated sickling of red blood cells leads to permanent deformation and premature erythrocyte destruction by macrophages and mechanical stress. This causes intra- and extravascular hemolysis, resulting in increased indirect bilirubin and lactate dehydrogenase and decreased haptoglobin. Haptoglobin binds circulating hemoglobin and reduces renal excretion of free hemoglobin, preventing tubular injury. Vasoocclusive symptoms: Patients with SCD may experience pain from hypoxic tissue injury and infarctions due to obstruction of small vessels by sickled cells. Microvascular occlusion typically involves the bone marrow, periosteum, and deep muscles but can occur in other organs. This patient is presenting with dactylitis (hand-foot syndrome), which results from small infarctions in the bones of the extremities. These infarctions cause swelling, tenderness, and warmth. Dactylitis is common in patients with SCD during the first few years of life as the affected bones still contain hematopoietic bone marrow. In older children and adults, vascular occlusion leads to pain crises, acute chest syndrome, leg ulceration, priapism, autosplenectomy, and stroke. Infections: Patients with SCD are predisposed to infections with encapsulated organisms (eg, Streptococcus pneumoniae) because repeated splenic infarcts cause functional asplenia. (Choices A and E) The chronic anemia in SCD can result in cardiomegaly due to chronically increased cardiac output (systolic function is largely preserved due to an increase in stroke volume). However, this typically does not occur until after infancy. Older patients can develop congestive heart failure due to ischemic cardiomyopathy and present with decreased cardiac output and increased systemic venous pressure. (Choices B and F) Serum albumin and urine cortisol excretion are typically normal in patients with SCD. (Choice C) Hereditary angioedema is a rare autosomal dominant disorder that is associated with painless episodes of swelling involving the face, lips, larynx, and extremities. It is caused by C1-inhibitor deficiency, not vasoocclusion. Educational objective: Dactylitis (painful swelling of the hands and feet) is a common presentation of sickle cell disease (SCD) in young children. It is one of many vasoocclusive manifestations of SCD. Sickling episodes result in hemolysis, which leads to increased indirect bilirubin and lactate dehydrogenase and decreased levels of haptoglobin. __________ References: Vaso-occlusion in sickle cell disease: pathophysiology and novel targeted therapies (http://www.ncbi.nlm.nih.gov/pubmed/24319205) Lactate dehydrogenase and hemolysis in sickle cell disease (http://www.ncbi.nlm.nih.gov/pubmed/23287628)

A 1-Year-Old African American Boy Is Brought to the Emergency