19 - Blood Flashcards
Vital functions of blood
- Transport oxygen
- Transport drugs
- Maintain fluid balance
- Important part of immune system
What is hematopoiesis? Where does it occur?
- Occurs in bone marrow in healthy adults
- Stem cells stimulated (poietins or colony-stimulating factors) to differentiate into committed cells that further mature
- The earlier the drug-induced hematological disorder (DIHD) occurs in the cascade of hematopoiesis (differentiation) the more severe the disorder
- Incidence of DIHD difficult to ascertain (0.01% drug-induced agranulocytosis)
Which drugs suppress bone marrow?
- Methotrexate
- Cyclophosphamide
- Colchicine
- Azathioprine
- Ganciclovir
What are the types of hematoxicity?
- Primary
- Secondary
- Idiosyncratic
What is primary hematotoxicity?
Direct cytotoxic mechanism or immunological mechanism
What is secondary hematotoxicity?
- Toxic effect a consequence of other tissue injury or systemic disturbances
- Damage caused by reactive/ compensatory mechanisms
Lab findings of anemia
Decreased RBC (count or volume) or decreased hemoglobin
Lab findings of polycythemia
Increased RBC (count or concentration)
Lab findings of thrombocytopenia
Decreased platelets
Lab findings of leukopenia
Decreased WBCs
Lab findings of granulocytopenia
Decreased neutrophils, eosinophils, and basophils
Lab findings of neutropenia
Decreased neutrophils
Lab findings of agranulocytosis
Very decreased neutrophils
Lab findings of pancytopenia
Decrease in all blood cells
Lab findings of hypocoagulability
Decreased clotting factors
What are the ways in which drugs may alter RBCs?
- Production
- Function
- Survival
How can drugs alter RBC production?
- Cell division/ hematopoiesis
- Hemoglobin synthesis => iron deficiency anemia
- Sideroblastic anemia
- Megaloblastic anemia
- Aplastic anemia
- Polycythemia
How can drugs alter RBC function?
- *Through effects on hemoglobin
- O2/ CO2 transport – shifts in oxygen dissociation curve => methemoglobinemia
How can drugs alter RBC survival?
- Normally ~ 120 days but shortened by oxidative injury, decreased metabolism, and/ or altered membrane => hemolytic anemia (immune-mediated or oxidative injury such as G6PD deficiency)
What is sideroblastic anemia?
Interference w/ heme synthesis
Causes of sideroblastic anemia? Is it reversible?
- EtOH
- Isonizaid (w/o vitamin B6 supplementation)
- Chloramphenicol
- Cycloserine
- Linezolid
- Zinc toxicity/ copper deficiency
- Lead intoxication
- Reversible w/ drug d/c
What is megaloblastic anemia?
Abnormal development of RBC precursors (megaloblasts)
What can cause megaloblastic anemia?
- Drugs w/ effect on DNA synthesis
- Folate and/or vitamin B12 deficiency from inadequate dietary intake or drugs