IC7 Anaemia & Drug-induced Haematological Disorders Flashcards
What are the 3 important things to do when you see a drop in Hg?
*3 impt things to assess
-
History
a. Recent bleeding events? Duration of bleeds
b. Chronic diseases e.g. CKD? Inflammatory diseases e.g. IBD?
c. Malignancy (can have bleeding) -
Physical Examination
a. Pallor
b. Jaundice (suggest increase hemolysis) -
Labs
a. FBC – Hb (female<11, male<13)
b. Reticulocyte count
c. Peripheral smear (to see MCV, microcytic, hypochromic, diff shape)
What are the lab values for the 4 different types of anaemia?
- MCV Low (Microcytic) → Serum Ferritin – low (+ TIBC – high) → Iron def anaemia
- MCV Low (Microcytic) → Serum Ferritin – normal/high → TIBC – low → Anaemia of chronic diseases
- MCV Normal → Reticulocyte count – high → hemolysis, splenic sequestration
- MCV High (Megaloblastic) → Folic acid (vit B9) def anaemia
OR Vit B12 (cobalamin) def anaemia
OR Drug induced
Differentiate the 2 types of microcytic anaemia.
- MCV Low (Microcytic) → Serum Ferritin – low (+ TIBC – high) → Iron def anaemia
- MCV Low (Microcytic) → Serum Ferritin – normal/high → TIBC – low → Anaemia of chronic diseases
What is ferritin and TIBC?
Ferritin – Fe stores in the body
TIBC – binding capacity, ability of transferrin to bind to Fe, thus “transport” of Fe
What is Fe def anaemia? What should you do after coming to the conclusion that it is IDA from the labs?
How do you manage IDA (name, dose, duration, ADR)?
Iron Deficient Anaemia:
- Think about why/what’s the cause/prompt?
o Blood loss
o Reduced Iron absorption (link to GI) - Address underlying cause
- Manage & treat IDA
o 30-40mg up to 200mg / day of elemental Fe
o 1000-1500mg / cycle of elemental Fe
o E.g. Ferrous gluconate (sangobion, 30mg), Fe polymaltose (100mg)
o TCU 3-6months
o ADR: constipation (some preps have sorbitol to reduce this), nausea
What are the causes of vit B12 (cobalamin) def Anaemia? How do you manage it?
Vit B12 Deficient Anaemia (Pernicious Anaemia)
Causes:
- Reduced absorption (e.g. autoantibodies to intrinsic factor, gastric disruption)
- Lack of vit B12 intake (found in meat)
- Other causes (e.g. PPIs, H2RA, H. pylori infection) –> high pH (alkaline) disrupt absorption of free Fe and vit B12
Management of Pernicious Anaemia:
Autoantibodies cause: IM or SC 1000mcg/day for 1 week → then 1000mcg/week for 4weeks → then 1000mcg/month for life
PO 1000mcg QD is absorbed by mass action, not reliant on action of intrinsic factors (sometimes early stage to the autoimmune disease, PO would still be effective)
o IM more painful than SC but more effective
Other causes: IV or SC 1000mcg OR 2000mcg daily OR PO vit B12
What is the cause of Folic acid def anaemia? How do you manage it (name, dose, duration)?
Folic Acid Deficiency Anaemia
Cause:
- Nutritional (common in developing countries)
Management:
1mg/day for 1-4months until haematologically recovered
Link blood cell lines with pathogenesis of anaemia
- Aplastic Anaemia – all cell lines affected (WBC, RBC, platelets)
- Hemolytic Anaemia – low RBC
- Agranulocytosis / Neutropenia – low neutrophils
- Thrombocytopenia – low platelets
How to diagnose drug-induce aplastic anaemia?
*What are the drugs causing drug-induce aplastic anaemia?
Drug-induced Aplastic Anaemia
Diagnosed when 2 out of the following:
- WBC <3500cells/mm3
- Platelet count <55000cells/mm3
- Hg<10g/dL AND reticulocyte count <30000cells/mm3
Drugs causing aplastic anaemia:
- **Cytotoxic chemotherapy
- Radiation therapy**
How to manage drug-induced aplastic anaemia?
Management:
- Withhold drug
-
Infection
a. When neutrophils < 500cells/mm3, give prophylaxis antibiotics and/or antifungals
b. IF febrile neutropenia, give broad spectrum antibiotics -
Bleeding (since platelets are low)
a. Transfusion support with erythrocytes and platelets
i. Might need Fe chelators (deferoxamine, deferasirox) in case Fe overload - HSCT + immunosuppressant (ciclosporine)
What are the drugs causing Drug-induced Agranulocytosis/Neutropenia?
How do you manage it?
Drugs causing aplastic anaemia:
- Anti-thyroid agent
- Clozapine and other phenothiazines
- Penicillins (beta-lactam)
Management:
- Withhold drug (blood cell count will return to norm in 2-4weeks)
- If neutrophils <100cells/mm3 → give filgrastim SC 300mcg/day
- Do NOT restart meds (anti-thyroid and clozapine)
- Restart penicillins at lower dose, after neutropenia has resolved without any recurrence of agranulocytosis
Patient groups at higher risk of mortality:
- Renal failure
- Bacteraemia
- Shock at the time of diagnosis
What are the unsafe and safe drugs for G6PD deficient Patients? What can the unsafe drugs lead to?
Drug-induced Hemolytic Anaemia specifically in G6PD deficient Patients (metabolic)
Unsafe drugs:
- Fluoroquinolone (ciprofloxacin, moxifloxacin)
- Primaquine
- Sulfonylureas (glipizide)
- Fava beans
- Henna
- Naphthalene (Mothballs)
Safe drug:
- Hydroxychloroquine, Chloroquine
What are the drugs causing drug-induced megaloblastic anaemia?
How to manage?
Drug-induced Megaloblastic Anaemia
Drugs causing + Management:
- Methotrexate – withhold drug
- Co-trimoxazole – folic acid
- Phenytoin/Phenobarbital – folic acid / switch to another ASM
How do you define drug-induced thrombocytopenia? What are the drugs causing it?
What is HIT?
How to manage it?
Drug-induced thrombocytopenia
**Diagnosed if:
- Platelet count <100,000cells/mm3 (100x10^9/L)
- OR greater than 50% reduction from baseline**
Other facts:
- Occurs usually 1-2weeks after starting meds / immediately
Drugs causing:
- UFH
- eptifibatide (GPIIb/IIIai)
Heparin-induced thrombocytopenia (HIT)
- Type II is significant
- Generally occur on 2nd or 3rd exposure to the drug –> thus need history taking
- Cross reactivity with LMWH (thus do not give, would give off label DOACs in Sg)
- Ironically causes thrombosis thus need IV thrombin inhibitor (Dabigatran, NA in Sg)
Management:
- Withhold meds
- KIV corticosteroids if severe HIT
- Do NOT restart the drug, as antibodies to the drug may persist for years
