Haemolytic Anaemias Flashcards
Define Anaemia
reduced haemoglobin level for the age and gender of the individual
What is haemolytic anaemia?
anaemia due to shortened RBC survival
What is the normal RBC lifecycle
- 2x1011 RBC/day in the bone marrow.
- RBC circulate for approx. 120 days without nuclei or cytoplasmic organelles.
- 300 miles travelled through microcirculation, as small as 3.5 microns.
- Removal senescent RBC by RES
Describe the process of haemolysis
- Shortened red cell survival to 30-80 days
- Bone marrow compensates by increasing production
- There are increased reticulocytes in circulation with or without nucleuses
What are the clinical findings in anaemia ?
- Jaundice
- Pallor
- fatigue
- Splenomegaly (enlarged spleen)
What are the chronic clinical findings
- Gallstones - pigment stones
- Leg ulcers - not healing due to lack of O₂ delivery
- Folate deficiency - due to increased use
What are the lab investigations carried out for HA
- Bone marrow findings
- Peripheral blood film
What would be seen in a Bone marrow investigation in HA
- Erythroid hyperplasia of BM, with normoblastic rxn, higher ratio of erythroid cells than myeloid cells
- Reticulocytosis – variable
Mild (2-10%) - Haemoglobinopathies
Moderate to marked (10-60%) - IHAs, HS, G6PD-def.
what would be seen in a peripheral blood film in HA
- Polychromatophilia, nucleated rbc, thrombocytosis; neutrophilia with left shift;
- Morphologic abnormalities provides clue to underlying disorder: e.g. Sickled cells, Spherocytes, Target cells, Schistocytes (fragmented, triangular rbc) acanthocytes
What are some other findings of HA
- Increased unconjugated bilirubin
- Increased LDH (lactate dehydrogenase)
- Decreased serum haptoglobin protein that binds free Hb
- Increased urobilinogen
- Increased urinary hemosiderin
How can Haemolytic anaemia’s be classified
Inheritance:
- Hereditary
Hereditary spherocytosis - Acquired
Paroxysmal nocturnal haemoglobinuria
Origin of RBC damage:
- Intrinsic (Intracorpuscular)
G6PD-deficiency - Extrinsic (Extracorpuscular)
Delayed Haemolytic Transfusion Rxn
Site of RBC destruction:
- Intravascular
Thrombotic Thrombocytopenic Purpura - Extravascular
Autoimmune Haemolysis
What is the site of RBC destruction
Extravascular - Liver then excreted in faeces
Intravascular - Kidney then excreted in urine
What are the intrinsic causes of HA
Membrane defects:
- Hereditary Spherocytosis (HS)
- Hereditary Elliptocytosis (HE)
- H. Pyropoikilocytosis
Enzyme defects:
- G6PD
- PK
Haemoglobin defects:
- Sickle Cell Disease
- Thalassaemia’s
What are the Immune-Mediated Extrinsic causes of HA
Autoimmune:
- Warm
- Cold
- Drug induced
Alloimmune:
- HDN
- Haemolytic Transfusion
What are the Non-Immune-Mediated Extrinsic causes of HA
Red cell fragmentation syn:
- Mechanical trauma
e.g. artificial valve - Microangiopathic HA
e.g. HUS, TTP, DIC
Drugs & chemicals
Infections:
- Malaria, clostridium
March haemoglubinuria
Hypersplenism