3 Flashcards
(257 cards)
2–year–old boy developed anemia after treatment with trimethoprim–sulfamethoxazole 3 weeks earlier. Hb and Hematocrit 7.2 g/dL and 24%. What is the diagnosis?
Glucose–6–phosphate dehydrogenase (G6PD) deficiency.
What is glucose–6–phosphate dehydrogenase deficiency?
Episodic hemolytic anemia. X–linked. Mediterranean, Middle Eastern, African, Asians. 24 hours after ingestion of oxidant (aspirin, sulfa drugs, antimalarials, fava), infection, illness. Rapid drop Hb, hemoglobinuria, jaundice. Reticulocytosis.
How is glucose–6– phosphate dehydrogenase deficiency diagnosed?
Direct measurement of G6PD activity.
What is the treatment for glucose–6–phosphate dehydrogenase deficiency?
Avoid oxidants, broad beans (ie, fava beans), primaquine, chloroquine, nitrofurantoin, ciprofloxacin, Pyridium, sulfonamides.
8–month–old, African–American infant with painful swollen hands and swollen feet. What is the diagnosis?
Sickle cell anemia.
What is the cause of sickle cell anemia?
Single base pair change (thymine for adenine) at the sixth codon of the beta gene (valine instead of glutamic acid).
What is the clinical presentation of sickle cell anemia?
Hemolytic anemia develops over first 2–4 months with the replacement of hemoglobin F. Hand–foot syndrome (dactylitis), which is a symmetric, painful swelling of hands, feet (ischemic bones).
What are acute sickle painful crises?
Characterized by pain in the extremities in younger. With increasing age, there is pain in the head, chest, back, abdomen.
What factors may precipitate a sickle painful crisis?
Precipitated by illness, fever, hypoxia, acidosis, or no precipitating factor can be identified.
What are the signs of vasoocclusive crises in sickle cell disease?
Skin ulcers, retinopathy, avascular necrosis of hip, infarction of bone and marrow (Salmonella osteomyelitis); splenic autoinfarction; acute chest syndrome; stroke (6–9 y); priapism in adolescence.
What is acute splenic sequestration?
Altered splenic function results in increased susceptibility to infection, especially with encapsulated bacteria (S. pneumococcus, H. influenzae, N. meningitidis). Peak 6 months to 3 years of age; can rapidly lead to death.
What is a sickle cell a plastic crisis?
Aplastic crisis occurs after infection with parvovirus B19; absence of reticulocytes during acute anemia.
How does sickle cell disease affect the kidneys?
Decreased renal function (proteinuria is the first sign); urinary tract infections.
What are the laboratory abnormalities in sickle cell anemia?
Increased reticulocytes, moderate anemia, normal MCV, nucleated RBCs. Blood smear shows target cells, poikilocytes, hypochromasia, sickle RBCs, nucleated RBCs, Howell–Jolly bodies (lack of splenic function). Bone marrow is hyperplastic.
How is sickle cell anemia diagnosed?
Newborn screening for hemoglobin S. Confirm diagnosis with hemoglobin electrophoresis. Prenatal diagnosis for parents with trait.
What is the treatment for sickle cell anemia?
Immunize with routine vaccines plus pneumococcal vaccine. Start penicillin prophylaxis at 2 months. Folate. Pain control; transfuse as needed. Oral hydroxyurea for patients with frequent painful crises. Bone–marrow transplant.
What is beta thalassemia major?
Excess alpha globin chains causes alpha tetramers to form; increase hemoglobin F. Presents in 2nd mth with anemia, hypersplenism, cardiac decompensation. Expansion of skull: extramedullary hematopoiesis; HSM.
What are the laboratory abnormalities in beta thalassemia major?
Infants with HbF only, which is detected by electrophoresis. Severe anemia, low reticulocytes, increased nucleated RBCs, hyperbilirubinemia, microcytosis. Increased ferritin and transferritin saturation. Marrow hyperplasia.
What is the treatment for beta thalassemia major?
Transfusions, deferoxamine, splenectomy. Bone–marrow transplant is curative.
What type of bleeding occurs in von Willebrand disease (vWD) or platelet dysfunction?
Mucous membrane bleeding, petechiae, small ecchymoses.
What type of bleeding occurs in clotting factor deficiency?
Deep bleeding with extensive ecchymoses and hematoma.
What is the initial evaluation of bleeding disorders?
Obtain platelets, bleeding time, PT, PTT. If initial tests are normal, check von Willebrand factor and thrombin time. If abnormal, obtain a clotting factor evaluation.
What is the purpose of testing bleeding time?
Tests platelet function and interaction of platelets with vessel walls; detects qualitative platelet defects or lack of von Willebrand factor.
What is the most common acquired cause of bleeding disorders in children?
Thrombocytopenia