IC7: Anemia and Drug-induced Haem Disorders

Question 1

What does MCV refer to

Answer 1

average volume of RBCs (RBC size)

Question 2

What does MCH refer to

Answer 2

amount of Hb in a RBC

Question 3

What are the microcytic anemias?

Answer 3

IDA, anemia of chronic disease

Question 4

What are the normocytic anemias?

Answer 4

blood loss, aplastic anemia

Question 5

What are the macrocytic anemias?

Answer 5

B12 deficiency, folate deficiency

Question 6

What are the lab values indicating iron-deficient anemia?

Answer 6

Low MCV, low ferretin (storage)

Question 7

What should be considered when a patient presents with IDA?

Answer 7

Causes of bleeding, especially for elderly patients or those on antithrombotics

Question 8

What does normal MCV and high reticulocyte count indicate?

Answer 8

Body’s response to acute blood loss, hemolysis or splenic sequestration

Question 9

What are the lab values indicative of AoCD?

Answer 9

Low MCV, normal/high ferretin (storage), low TIBC (cannot utilise)

Question 10

What are the 2 mechanisms by which IDA may occur?

Answer 10

Decreased iron absorption (GI conditions like H. pylori, gastritis)
Blood/iron loss

Question 11

When should iron supplementation be given and how should it be given?

Answer 11

When suspect that deficiency is nutritional (no bleed after scope)

1000-1500mg elenental iron for 3-6 months

Question 12

What are the two most common iron sources and what are their % of elemental iron?

Answer 12

Iron polymaltose 100%

Ferrous gluconate (sangobion) 12%

Question 13

What is the most prominent SE of taking iron?

Answer 13

GI discomfort

Question 14

What are the causes of AoCD? (8)

Answer 14

malignancy, HIV infection, rheumatologic disorders, IBD, Castleman disease, heart failure, renal insufficiency and COPD

Question 15

How does chronic inflammation lead to anemia?

Answer 15

States of chronic inflammation can lead to the release of hepcidin which leads to decreased iron absorption

Question 16

What are the 3 causes of vitamin B12 deficiency?

Answer 16

• 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)

Question 17

How should pernicious anemia (B12 deficiency) be treated if the patient has intrinsic factor deficiency?

Answer 17

IM/SC vitamin B12 given 1000μg OD for one week followed by 1000mμg weekly for 4 weeks then 1000μg monthly for life

Question 18

How should pernicious anemia (B12 deficiency) be treated if the patient does not have intrinsic factor deficiency?

Answer 18

PO vitamin B12, 1000μg or 2000μg daily

Question 19

How should folate deficiency be treated?

Answer 19

folic acid 1mg/day for 1-4 months or until hematologic recovery is achieved

Question 20

What does aplastic anemia affect?

Answer 20

neutrophils, platelets, red cells

Question 21

What does agranulocytosis affect?

Answer 21

neutrophils

Question 22

What does hemolytic anemia affect?

Answer 22

red cells

Question 23

What does thrombocytopenia affect?

Answer 23

platelets

Question 24

What are the 3 criteria that are affected by aplastic anemia (2/3)

Answer 24

WBC count
platelet count
Hb + reticulocyte count

Question 25

What are some of the drugs that can cause aplastic anemia? (7)

Answer 25

CBZ, PBT, PHT, PTU, sulfonamides, chloramphenicol, lithium

Question 26

What other pharmacotherapy can be considered in aplastic anemia and when should it be given?

Answer 26

prophylactic antibiotic and antifungal agents should be initiated with neutrophil counts are below 500 cells/mm3

Question 27

What is the ANC count for neutropenia?

Answer 27

< 1500 cells/μL

Question 28

What 3 classes of drugs are commonly implicated in agranulocytosis?

Answer 28

Antipsychotics, antibiotics and antithyroid medication

Question 29

What drug can be started for extremely low neutrophil counts in agranulocytosis?

Answer 29

G-CSF (figrastim)

Question 30

What are the two main etiology for hemolytic anemia?

Answer 30

Immune (IgG/IgM mediated, drug-induced)

Metabolic (G6PD deficiency)

Question 31

What are the two broad classes of drugs that cause hemolytic anemia in G6PD deficiency?

Answer 31

Sulfonylureas and FQs

Question 32

What are the 4 drugs that can precipitate megaloblastic anemia?

Answer 32

• 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)

Question 33

What is the criteria for thrombocytopenia

Answer 33

Platelet count ≤ 100,000 cells/mm3 (100 x 10^9/L) or greater than 50% reduction from baseline values

Question 34

What is the onset like for drug-induced thrombocytopenia? (2)

Answer 34

• 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)

Question 35

What condition is heparin-induced thrombocytopenia paradoxically associated with?

Answer 35

Thrombosis

Question 36

What about the offending drug should be taken note of for thrombocytopenia?

Answer 36

It should not be restarted indefinitely due to the formation of antibodies