Heme/Onc Flashcards
Where does hematopoiesis happen?
Starts in secondary yolk sac
Liver takes over around week 5-6 (primary site till week 22)
Bone marrow takes over between weeks 8-19, primary site after week 22
Hb electrophoresis in sickle cell?
Hb S and Hb F, no Hb A
Protein abnormality in sickle cell?
Valine for glutamic acid at position 6, abnormal beta globin
Most common hemoglobinopathy in the world and which chromosome is the abnormality on?
Hemoglobin E, chromosome 11
Abnormality leading to decreased production of beta globin chains
When should a NBS be repeated if altered by a transfusion?
2 months after last transfusion
How many mL of fetal blood in 1% HbF
50 mL
What causes false negative KB test results?
Blood group incompatibility leading to accelerated clearance from maternal circulation
Bone marrow with absent erythroid precursors is seen in which syndrome?
Diamond Blackfan
Also with triphalangeal thumbs
Etiology of Fanconi anemia
Autosomal recessive, chromosomal instability with breakage. It can be tested with mitomycin C
Which virus causes erythroid aplasia
Parvovirus B 19
What type of blood incompatibility is associated with more severe disease with subsequent pregnancies?
Rh incompatibility.
ABO is NOT more severely affected with subsequent pregnancies, and may occur in the first
When is RhoGam administered?
28 weeks and delivery, after any invasive procedures, and within 72 hours of delivery of Rh-positive infant
How is monitoring for fetal anemia done?
Monitor middle cerebral artery peak systolic velocity by ultrasound
Severe risk if MCA greater than 1.5 multiples of the median
Which minor blood group antigens do not cause hemolytic disease?
Lewis antigen (does cause positive Coombs)
Anti I
Anti Fyb
Which antigens cause most severe expression of hemolytic disease?
Rh, followed by Kell
Duffy (Fya) and Kidd also but have low overall prevalence
Most frequently inherited enzyme defect?
G6PD deficiency
Most common complication after an exchange transfusion?
Thrombocytopenia, because the whole blood doesn’t contain platelets
HypOcalcemia may be seen (due to preservatives)
Hypotension may occur during the procedure
Formula to calculate blood volume exchanged?
(Observed Hct - desired Hct)/observed Hct x infant’s blood volume
What is an infant’s blood volume?
80-100 ml/kg
Term closer to 80/kg
Preterm closer to 100/kg
Most commonly implicated antigen in whites in NAIT?
HPA-1a. Also known as PLA1
HPA4b in other races
Vitamin K dependent factors?
Factor 2, 7, 9 and 10
Syndromes with an increased risk of congenital leukemia?
Fanconi’s anemia, Diamond-Blackfan syndrome, trisomy 21
Most common solid tumor in the neonatal period and its major site?
Teratoma, 50% in sacrococcygeal region
What is hemoglobin Barts?
4 gamma globin chains - tetramers
What is hemoglobin H?
Beta globin tetramers
Diagnostic testing for hereditary spherocytosis?
Flow cytometric osmotic fragility test and eosin 5 maleimide (EMA) test (this is preferred now, osmotic fragility requires a lot of blood)
Drugs that induce indirect hyperbili?
Ceftriaxone, sulfonamides, indomethacin
Difference between neonatal alloimmune and autoimmune thrombocytopenia?
Autoimmune: maternal and infant’s platelets are low. Mother has autoimmune disorder, antibodies destroy both mom’s and infant’s platelets
Alloimmune: infant’s platelets are low, mother’s are normal.
Hallmark lab findings with TMD?
Leukocytosis with neutrophils
Thrombocytopenia
Blasts on blood smear
Chemotherapy does not prevent the occurrence of leukemia
When does peak iron transfer in the fetus occur?
After 30 weeks gestation
What is the total body iron content in a term infant?
75 mg/kg - about 80% is in hemoglobin
How does heparin work? Most important factors inhibited by heparin?
Antithrombin III mediated inactivation of coagulation factors. Most importantly factors Xa and IIa
Factors responsible for subtherapeutic heparin levels/resistance?
Inadequate concentrations of antithrombin
Increased clearance of heparin
Increased binding of heparin to plasma proteins
Increased concentration of fibrinogen, or factor VIII
How is heparin cleared?
- Degradation in epithelial cells and macrophages
2. Renal clearance (Neonates and young infants have faster clearance of heparin than do children and adults)
Assays used to identify and quantify fetal blood in maternal circulation?
Kleihauer-Betke assay and flow cytometry.
Basis of Kleihauer-Betke test?
difference in acid solubility between hemoglobin A and F
HbA becomes ghost cells
How do you prevent transfusion associated graft versus host disease?
Irradiation (also reduces shelf life to 28 days)
What does leukoreduction prevent?
Decreases febrile nonhemolytic transfusion reactions by 60% Decreases viral (cytomegalovirus) transmission, and HLA alloimmunization.
