A 3-year-old boy is brought to the clinic due to decreased energy and yellow skin. The patient first became ill 2 days ago when he developed a runny nose and cough. Yesterday, he had abdominal pain with nausea, but he has not had vomiting or diarrhea. The mother also noticed yellowing of the patient's eyes and skin, and this morning he did not want to play or eat. Medical history includes similar yellowing of the skin after birth that required phototherapy. Otherwise, he has been healthy. Several members of his family had similar intermittent episodes of skin yellowing during childhood, and 2 relatives underwent splenectomies in adulthood. The patient takes no medications. Physical examination shows a tired-appearing toddler with mild jaundice. Eye examination shows mild scleral icterus. The abdomen is soft and tender in the left upper quadrant. The spleen is 4 cm below the costal margin. The remainder of the examination shows no abnormalities. Laboratory results are as follows:
Additional evaluation of this patient would most likely reveal which of the following laboratory findings?

Question

A 3-year-old boy is brought to the clinic due to decreased energy and yellow skin.  The patient first became ill 2 days ago when he developed a runny nose and cough.  Yesterday, he had abdominal pain with nausea, but he has not had vomiting or diarrhea.  The mother also noticed yellowing of the patient's eyes and skin, and this morning he did not want to play or eat.  Medical history includes similar yellowing of the skin after birth that required phototherapy.  Otherwise, he has been healthy.  Several members of his family had similar intermittent episodes of skin yellowing during childhood, and 2 relatives underwent splenectomies in adulthood.  The patient takes no medications.  Physical examination shows a tired-appearing toddler with mild jaundice.  Eye examination shows mild scleral icterus.  The abdomen is soft and tender in the left upper quadrant.  The spleen is 4 cm below the costal margin.  The remainder of the examination shows no abnormalities.  Laboratory results are as follows: 
Additional evaluation of this patient would most likely reveal which of the following laboratory findings?

Quizplus · Accepted Answer

11ec25c8_d6a3_3651_bc81_495287a4b40f_MD0003_00 This patient has splenomegaly and signs of hemolysis (anemia, jaundice) following an upper respiratory illness. These clinical features, along with a family history of multiple relatives requiring splenectomy, make hereditary spherocytosis (HS) the most likely cause of his hemolytic anemia. HS is usually due to an autosomal dominant defect in red blood cell (RBC) membrane proteins (eg, spectrin, ankyrin) that results in sphere-shaped, fragile RBCs. Due to their shape, these abnormal RBCs get trapped and destroyed in the spleen. In all types of hemolytic anemia, the bone marrow produces increased reticulocytes in response to RBC destruction. However, elevated mean corpuscular hemoglobin concentration (MCHC) (due to membrane loss and RBC dehydration) distinguishes HS from other forms of hemolysis. Other laboratory findings include low to normal mean corpuscular volume, negative direct Coombs test, and spherocytes on peripheral smear. Treatment involves supportive care (eg, folic acid, transfusions) and splenectomy for severe hemolysis. spherocytes (Choice B) Glucose-6-phosphate dehydrogenase deficiency, which can also present with jaundice and splenomegaly and affect different family members (X-linked recessive inheritance pattern), would cause elevated reticulocytes, negative direct Coombs test, and low (rather than high) MCHC. However, management is with avoidance of hemolytic triggers rather than splenectomy. This patient's family history of several relatives requiring splenectomies makes HS a much more likely diagnosis. (Choice C) Warm autoimmune hemolytic anemia (AIHA) can present with jaundice and splenomegaly but is characterized by a positive direct Coombs test. AIHA may be triggered by an upper respiratory illness but is unlikely to involve multiple family members because it is not inherited like HS. In addition, autoantibody production is rarely seen in the newborn period. (Choice D) A patient with HS will have abnormally low reticulocytes in the case of a transient aplastic crisis (eg, parvovirus infection). This patient has no signs of concurrent parvovirus infection (eg, fever, rash). (Choice E) Low reticulocytes, negative direct Coombs test, and normal MCHC are normal findings that would not be expected in a child with signs of hemolytic anemia. Educational objective: Hereditary spherocytosis (HS) is a genetic defect in red blood cell (RBC) membrane proteins that results in sphere-shaped RBCs. HS should be suspected in a patient with jaundice, splenomegaly, and a family history suggestive of hemolytic anemia requiring splenectomy. Laboratory findings include elevated reticulocytes and mean corpuscular hemoglobin concentration and negative direct Coombs test. References: Guidelines for the diagnosis and management of hereditary spherocytosis--2011 update. (http://www.ncbi.nlm.nih.gov/pubmed/22055020)

A 3-Year-Old Boy Is Brought to the Clinic Due to Decreased