Anaemia Flashcards
Causes of microcytic anaemia (MCV <80)?
TAILS
- Thalassemia
- ACD
- IDA
- Lead poisoning
- Sideroblastic anaemia
Causes of normocytic anaemia?
ABCD
- Acute blood loss
- BM failure (BM failure, leukaemia, AA, pure red cell aplasia)
- Chronic disease
- Destruction (haemolysis)
Causes of macrocytic anaemia (mcv >100)
FAT RBC
- Folate deficiency / Fetus (pregnancy)
- Alcohol / Liver disease / Cirrhosis
- Thyroid (hypothyroidism)
- Reticulocytosis (compensatory)
- B12 deficiency / BM (MDS)
- Cirrhosis / CLD
What is your work-up for microcytic anaemia? - what are 3 key tests and what do you look for that may help you distinguish between different causes?
Key test = iron studies. Blood film (look for spherocytes - HS) and Hb electrophoresis (thalassaemia)
Low iron + low ferritin + high TIBC → iron deficiency
Low/normal iron + low/normal ferritin + low TIBC → ACD with IDA
What is the key test to distinguish different causes of normocytic anaemia?
Reticulocytes.
If <2% → suggest BM failure (infection driven BM failure, leukaemia, aplastic anaemia, red cell aplasia…etc)
If >2% → suggest increased production - i.e. blood loss or haemolytic anaemia
What is the most important test (not B12/folate) for a patient with macrocytic anaemia to identify the cause?
Blood film. You want to distinguish between megaloblastic vs. non-megaloblastic causes.
If blood film shows megalocytes and hyper-segmented neutrophils → indicate megaloblastic anaemia (i.e. impairmed DNA synthesis).
Causes:
Megaloblastic anaemia: B12/folate def, drug-induced (e.g. hydroxyurea)
Non-megaloblastic: alcohol/liver disease, MDS/Congenital BM failure
Leuko-erythro-blastic pattern in blood film - DDx (2)?
- This means there are nucleated RBCs and immature white cells → usually indicates marrow replacement. E.g.
- BM fibrosis
- BM infiltration by tumour cells (e.g. metastatic Ca)
Causes of nucleated RBCs on blood film? (3)
Always abnormal
Signifies stressed erythropoiesis or extra-medullary erythropoiesis
Causes
- Haematological: SCD, thalassemia, haemolytic anaemia after splenectomy
- Leukoerythroblastic film – BM replacement as before
- Severe systemic illness: Sepsis, severe HF
Following blood film findings are linked to…
- Helmet cells & schistocytes
- Microspherocytes
- Teardrop RBCs
- Leukoerythroblastic
- Bite cells
- Helmet cells & schistocytes – MAHA (i.e. mechanical hemolysis)
- Microspherocytes – AIHA
- Teardrop RBCs – MF
- Leukoerythroblastic – BM replacement
- Bite cells – oxidative haemolysis or parasites (e.g. malaria)
Causes of iron deficiency anaemia?
- Blood loss (GIT, uterine ca)
- ↓ absorption – celiac, atrophic gastritis, bariatric surgery, H.pylori
- Intravascular haemolysis
- Pregnancy
Diagnostic criteria for IDA?
- Ferritin <30
- TSAT <19% (no consensus on cut-off, some uses <16%), lower → more specific
- Anaemia that resolves upon iron administration
- NOT iron level – it can be low in ACD or inflammatory state or increased by recent iron consumption
- TSAT can also be elevated by food/iron tablets
- Soluble transferrin receptor high (sTFR) → as RBCs produce more transferrin receptors in their thirst for Fe (normal in ACD). Care also low in CKD (due to low EPO)
MCH and MCHC - What does it mean?
Mean Corpuscular Haemoglobin = Hb content in a RBC.
MCHC = Mean Corpuscular Hb Concentration = average Hb concentration in RBC.
Low MCH can indicate IDA or hemoglobinopathies like thalassma. Typically they have hypochromia in the peripheral blood smear.
Very low MCHC is typical of IDA, very high MCHC typically reflect spherocytosis.
RDW - what is it and what does high/low value indicate?
Red cell distribution width - measures variation in RBC size.
High RDW = large variation in RBC size → seen in IDA, MDS, Hemoglinopathies, transfusions. Confirm with blood fil,.
Low RDW = more homogeneous populaiton.
HCT - what is it?
is same as PCV (Packed Cell Volume)
= proportion of blood that is made of cells.
So HCT increases in dehydration, decreases with haemodilution.
