Heme Pharm Flashcards
What does the bone marrow of a healthy fetus produce each day?
Millions of cells
This is crucial for maintaining stable cell numbers as the baby grows.
What are the associated hematologic conditions resulting from preterm birth or illness?
Anemia and neutropenia
Anemia is characterized by insufficient red blood cells, while neutropenia involves lower than normal levels of neutrophils.
What is erythropoietin (Epo)?
An endogenous glycoprotein hormone that regulates erythrocyte production.
What is the effect of recombinant human erythropoietin (rhEpo) on transfusion needs?
Decreases the need for transfusions
RhEpo is used to treat or prevent anemia of various causes.
Where does embryonic and fetal erythropoiesis occur?
Yolk sac, ventral aspect of the aorta, liver, and bone marrow.
What factors are important for definitive erythropoiesis?
- Epo
- Stem cell factor (c-kit ligand)
- Interleukin (IL) 3 and 6
- Granulocyte macrophage colony stimulating factor (GM-CSF)
- Potentially insulin and insulin-like growth factor
How does Epo maintain red blood cell production?
By inhibiting apoptosis of erythroid progenitor cells and stimulating their proliferation and differentiation into normoblasts.
What happens to serum Epo concentrations in healthy term infants after birth?
They decrease to a nadir between 4-6 weeks.
What are the contributors to preterm anemia?
- Phlebotomy loss
- Short red blood cell life
- High growth requirements
- Iron deficiency
- Inflammatory states
What characterizes anemia of prematurity?
Lower hemoglobin levels at birth compared to term infants, earlier and more pronounced postnatal decline.
What is the primary cause of anemia of prematurity?
Impaired ability to increase serum Epo appropriately in the setting of anemia and decreased tissue oxygen availability.
How can Epo be administered?
By IV infusion or subcutaneous injection.
What is the half-life of Epo in preterm infants?
5-8 hours.
What are the adverse effects of Epo in preterm infants?
Very safe; adverse effects noted in adults are not seen in preterms.
What is different about neonatal haemostasis compared to adults?
All aspects of the coagulation system are affected by low levels of procoagulants except for factors V and VIII, and von Willebrand factor.
What happens to platelet levels by 22 weeks of gestation?
A well fetus has adult levels of platelets.
What is the effect of reduced antithrombin III levels in neonates?
It likely causes relative resistance to heparin anticoagulants.
What is the normal prothrombin time (PT)?
Approximately 12 seconds.
What does partial thromboplastin time (PTT) measure?
Coagulation throughout the intrinsic and common pathways.
What is the starting dose of unfractionated heparin for prophylaxis?
10 units/kg/hr.
What is the mechanism of action of unfractionated heparin?
Indirectly inhibits clotting factors thrombin and Xa.
What is the target anti-Xa level for all ages?
0.35/0.7 u/ml.
What is the common complication of heparin therapy?
Heparin induced thrombocytopenia.
What is the dosing for low molecular weight heparin (enoxaparin)?
1.8 mg/kg/dose.
