Flashcards in Hematology Deck (122)
What is hemoglobin A comprised of?
a tetramer consisting of one pair of alpha globin chains and one pair of beta globin chains
What is the defect in beta thalassemia?
impaired production of beta globin chains, leading to a relative excess of unstable alpha globin chains
What happens when you have excess alpha globin chains (as in beta thal)?
Excess alpha globin chains are unstable, incapable of forming soluble tetramers on their own, and precipitate within the cell, leading to a variety of clinical manifestations. The degree of alpha globin chain excess determines the severity of subsequent clinical manifestations, which are profound in patients homozygous for impaired beta globin synthesis
How do infants with beta thalassemia present at birth?
Infants with severe beta thalassemia major (BTM) are well at birth, because the production of beta globin is not essential during fetal life or the immediate perinatal period. The major non-alpha globin produced at the time of birth is gamma globin, such that the major hemoglobin in early postnatal life is fetal hemoglobin (Hb F, alpha2/gamma2).
When would an infant develop symptoms of beta thalassemia major?
During the second six months of life when gamma globin chain production decreases and should be replaced with the production of beta globin to form adult hemoglobin (Hb A, alpha2/beta2).
What is the classic xray finding in beta-thalassemia?
hair-on-end apperance of the skull
What is the Mentzer index?
(if >13 iron deficiency is more likely)
What is neonatal alloimmune thrombocytopenia (NAIT)?
fetal platelets contain an antigen inherited from the father that the mother lacks, most commonly human platelet antigen (HPA)-1a
What is the most likely cause for inability to reach therapeutic heparin level despite increasing doses?
Antithrombin III deficiency
1st line treatment for DVT?
Low molecular weight heparin
What does bone marrow aspirate show in transient erythroblastopenia of childhood?
Arrested erythroid precursors
What are predictors of poor outcome in sickle cell disease?
What are the 3 main features of Wiskott-Aldrich?
(1) Severe eczema
(3) Frequent infections
What would be the reason for increasing episodes of bleeding and hemarthrosis of the ankle despite meditation compliance?
Check FVIII and inhibitor levels
Types of Von Willebrand disease
Type 1 -Decrease in quantity
Type 2 - Abnormal quality
Type 3 - No VWF (most rare)
Medications used in VWD
DDAVP - increases release of VWF
*will not work in Type 2, Type 3
What is the antigen implicated in NAIT?
HPA-1A (used to be called PLA-1) *give PLA-1 negative platelets)
What is the pathophysiology/process in NAIT?
Caused by antibodies specific for platelet antigens inherited from the father but which are absent in the mother (analogous to Rh-)
What are the vitamin K-dependent factors?
10, 9, 7, 2
When does the classic form of hemorrhagic disease of the newborn present?
1 day - 2 weeks (not enough placental transfer from mom)
When does the early form of hemorrhagic disease of the newborn present?
< 24 hrs
When does the late form of hemorrhagic disease of the newborn present?
2 weeks - 12 weeks (exclusively in breastfed infants - not taking enough vitamin K)
Features of DIC
Elevated D-dimer, low platelets, low fibrinogen, elevated INR/PTT
Conditions associated with polycythemia
T21, recipient twin, LGA, maternal diabetes, Beckwith-Wiedemann, thyroid abnormalities, chromosomal abnormalities
Timing of physiologic hemoglobin nadir in preterm vs. term babies?
Term - 6 to 8 weeks
Preterm - 3 to 7 weeks
What do you see on the blood smear for a child with HUS?
Schistocytes (sign of intravascular hemolysis)
Signs of Diamond Blackfan anemia on physical exam
abnormal thumbs (long, bifid), absent radial pulse, craniofacial abnormalities
What is the objective of using leukoreduced white cells?
To prevent febrile transfusion reactions
What is Shwachman-Diamon syndrome?
Shwachman-Diamond syndrome (SDS, also known as Shwachman-Bodian-Diamond syndrome, Shwachman-Diamond-Oski syndrome, or Shwachman syndrome) is a rare inherited disorder associated with neutropenia that may progress to bone marrow failure, exocrine pancreatic insufficiency, and skeletal abnormalities that generally presents in infancy.