IC7: Anemia and Drug-induced Haem Disorders Flashcards
What does MCV refer to
average volume of RBCs (RBC size)
What does MCH refer to
amount of Hb in a RBC
What are the microcytic anemias?
IDA, anemia of chronic disease
What are the normocytic anemias?
blood loss, aplastic anemia
What are the macrocytic anemias?
B12 deficiency, folate deficiency
What are the lab values indicating iron-deficient anemia?
Low MCV, low ferretin (storage)
What should be considered when a patient presents with IDA?
Causes of bleeding, especially for elderly patients or those on antithrombotics
What does normal MCV and high reticulocyte count indicate?
Body’s response to acute blood loss, hemolysis or splenic sequestration
What are the lab values indicative of AoCD?
Low MCV, normal/high ferretin (storage), low TIBC (cannot utilise)
What are the 2 mechanisms by which IDA may occur?
Decreased iron absorption (GI conditions like H. pylori, gastritis)
Blood/iron loss
When should iron supplementation be given and how should it be given?
When suspect that deficiency is nutritional (no bleed after scope)
1000-1500mg elenental iron for 3-6 months
What are the two most common iron sources and what are their % of elemental iron?
Iron polymaltose 100%
Ferrous gluconate (sangobion) 12%
What is the most prominent SE of taking iron?
GI discomfort
What are the causes of AoCD? (8)
malignancy, HIV infection, rheumatologic disorders, IBD, Castleman disease, heart failure, renal insufficiency and COPD
How does chronic inflammation lead to anemia?
States of chronic inflammation can lead to the release of hepcidin which leads to decreased iron absorption
What are the 3 causes of vitamin B12 deficiency?
- reduced absorption (lack of intrinsic factor (required for B12 absorption) or gastric disruption)
- nutrition (B12 exclusively found in meats)
- other causes (PPIs, H2RAs, H. pylori infection)
How should pernicious anemia (B12 deficiency) be treated if the patient has intrinsic factor deficiency?
IM/SC vitamin B12 given 1000μg OD for one week followed by 1000mμg weekly for 4 weeks then 1000μg monthly for life
How should pernicious anemia (B12 deficiency) be treated if the patient does not have intrinsic factor deficiency?
PO vitamin B12, 1000μg or 2000μg daily
How should folate deficiency be treated?
folic acid 1mg/day for 1-4 months or until hematologic recovery is achieved
What does aplastic anemia affect?
neutrophils, platelets, red cells
What does agranulocytosis affect?
neutrophils
What does hemolytic anemia affect?
red cells
What does thrombocytopenia affect?
platelets
What are the 3 criteria that are affected by aplastic anemia (2/3)
WBC count
platelet count
Hb + reticulocyte count
What are some of the drugs that can cause aplastic anemia? (7)
CBZ, PBT, PHT, PTU, sulfonamides, chloramphenicol, lithium
What other pharmacotherapy can be considered in aplastic anemia and when should it be given?
prophylactic antibiotic and antifungal agents should be initiated with neutrophil counts are below 500 cells/mm3
What is the ANC count for neutropenia?
< 1500 cells/μL
What 3 classes of drugs are commonly implicated in agranulocytosis?
Antipsychotics, antibiotics and antithyroid medication
What drug can be started for extremely low neutrophil counts in agranulocytosis?
G-CSF (figrastim)
What are the two main etiology for hemolytic anemia?
Immune (IgG/IgM mediated, drug-induced)
Metabolic (G6PD deficiency)
What are the two broad classes of drugs that cause hemolytic anemia in G6PD deficiency?
Sulfonylureas and FQs
What are the 4 drugs that can precipitate megaloblastic anemia?
- antimetabolites → like MTX which is the most well known, and should be held off
- co-trimoxazole → especially in B12/folate deficiency (give folinic acid 5-10mg up to QDS)
- phenytoin and phenobarbital → inihibits folate absorption or catalyses folate metabolism (give folic acid 1mg/day)
What is the criteria for thrombocytopenia
Platelet count ≤ 100,000 cells/mm3 (100 x 10^9/L) or greater than 50% reduction from baseline values
What is the onset like for drug-induced thrombocytopenia? (2)
- Typically presents 1-2 weeks after a new drug is initiated, but may present immediately after a dose when an agent has been used intermittently in the past (eg. UFH)
- Rapid onset may also occur with the GPIIb/IIIa inhibitor class of drugs (eg. eptifibatide)
What condition is heparin-induced thrombocytopenia paradoxically associated with?
Thrombosis
What about the offending drug should be taken note of for thrombocytopenia?
It should not be restarted indefinitely due to the formation of antibodies
