A 2-week-old girl is brought to her primary care provider for a routine visit. The patient was born by normal spontaneous vaginal delivery at 39 weeks gestation. The mother is breastfeeding exclusively, and the infant has regained her birth weight. Newborn screening results from hemoglobin electrophoresis are as follows: The patient's mother has sickle cell trait, and a maternal cousin has sickle cell anemia. Examination shows a well-appearing infant with no pallor or splenomegaly. Which of the following is most likely true about this patient?

Question

A 2-week-old girl is brought to her primary care provider for a routine visit.  The patient was born by normal spontaneous vaginal delivery at 39 weeks gestation.  The mother is breastfeeding exclusively, and the infant has regained her birth weight.  Newborn screening results from hemoglobin electrophoresis are as follows:  The patient's mother has sickle cell trait, and a maternal cousin has sickle cell anemia.  Examination shows a well-appearing infant with no pallor or splenomegaly.  Which of the following is most likely true about this patient?

Quizplus · Accepted Answer

11ec160b_3995_26b2_9249_dd9c7072e8c4_MD0001_00 This patient's hemoglobin electrophoresis from her newborn screen is most consistent with sickle cell trait. At birth, infants who are heterozygous for sickle cell trait typically have the greatest amount of fetal hemoglobin (Hb F), followed by hemoglobin A (Hb A), and the smallest amount of hemoglobin S (Hb S). Hb A continues to be higher than Hb S throughout the lifetime of these patients as Hb F naturally declines, offering protection from sickle cell anemia, aplastic crises, and splenic sequestration. Patients with sickle cell trait are usually asymptomatic with normal hemoglobin level, reticulocyte count, and red blood cell (RBC) indices. However, they may develop hematuria, priapism, and increased incidence of urinary tract infections. Splenic infarction at high altitudes has also been reported. Patients with sickle cell trait have relative protection from Plasmodium falciparum (malaria), resulting in lower rates of severe malaria and hospitalization than seen in the general population. Possible mechanisms include increased sickling of parasitized sickle cell trait RBCs and accelerated removal of these cells by the splenic monocyte-macrophage system. These patients are not immune to malaria, however, and those visiting malaria-endemic areas should still receive prophylaxis. (Choice A) Life expectancy of patients with sickle cell trait is no different than that of the general population. Patients who are homozygous for the sickle cell mutation have a decreased life expectancy due to significant complications of disease (eg, acute chest syndrome, infection from encapsulated organisms). (Choices B and C) Patients with sickle cell trait typically have normal RBC indices and reticulocyte counts. Individuals with sickle cell anemia (eg, no normal Hb A) will have an elevated reticulocyte count but will maintain a normal mean corpuscular volume. (Choice E) It is unlikely that this patient will develop painful crises as she is protected by the predominance of Hb A (normal hemoglobin) over Hb S. Vaso-occlusive pain crises that develop in patients with sickle cell anemia are thought to occur when Hb S polymerizes and causes the RBCs to assume a sickle shape, typically in response to a trigger (eg, cold weather, dehydration). Educational objective: Patients with sickle cell trait are typically asymptomatic and have relative protection from malaria caused by Plasmodium falciparum. These patients usually have normal hemoglobin, reticulocyte, and red blood cell index values. Life expectancy is the same as that of the general population. __________ References: Complications associated with sickle cell trait: a brief narrative review. (http://www.ncbi.nlm.nih.gov/pubmed/19393983) Sickle cell trait protects against Plasmodium falciparum infection. (http://www.ncbi.nlm.nih.gov/pubmed/23035141)

A 2-Week-Old Girl Is Brought to Her Primary Care Provider