IOD Haemolytic Anaemia Flashcards

1
Q

What is haemolytic anaemia?

A

Increased peripheral destruction of RBCs
Shortened RBC life span (normally 120 days)

Bone marrow continues to produce cells
Pathology is in the red cell itself, or it’s environment

Increased consumption means BM has to work harder to compensate.
As the BM tries to keep up, the patient becomes anaemic
RBC destroyed > RBC produced

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2
Q

Categories of haemolysis?

A
Inherited-present from birth
Immune-Antibody mediated 
Extravascular-site of destruction is the
spleen and other RES
organs 
Acquired-Develops de novo 
Non-immune-RBC or environment
Intravascular-site of destruction is within  the vascular space
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3
Q

Inherited non-immune types?

A

Sickle cell disease-extravascular & intravascular
Membrane disorders-eg Hereditary Spherocytosis extravascular
G6PD deficiency -
intravascular

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4
Q

acquired non immune problem with RBC?

A

Paroxysmal Nocturnal Haemoglobinuria (PNH)

intravascular

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5
Q

acquired non immune problem with RBC environment?

A
Microangiopathic haemolysis (MAHA): 
TTP, DIC, HELLP 
intravascular
Valve haemolysis
intravascular
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6
Q

Acquired Immune AB-mediated attack on RBC’s?

A

Autoimmune: warm, cold, drug induced
intravascular & extravascular
Alloimmune – transfusion reactions, HDFN intravascular

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7
Q

Investigations?

A

Haemolysis Screen

FBC: Normocytic anaemia
Blood film: Spherocytes or red cell fragments
Reticulocytes: Increased
LDH: Increased (due to cell turnover)
Bilirubin (on RBC membranes):Increased (unconjugated)
Haptoglobin (binds to free Hb in plasma to remove it):Decreased in intravascular haemolysis
DAT: Positive in some immune cases

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8
Q

Intravascular results?

A
↑ unconjugated bilirubin
↑ LDH
↑ Reticulocytes
↓ haptoglobin
Haemoglobinuria
Haemoglobinaemia
Haemosiderinuria
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9
Q

extravascular

A
↑ unconjugated bilirubin
↑ LDH
↑ Reticulocytes
normal haptoglobin
No Haemoglobinuria
No Haemoglobinaemia
No Haemosiderinuria
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10
Q

Acquired immune haemolytic anaemia types?

A
Auto-immune-self as foreign
Warm AIHA
Cold AIHA
Cold Haemagglutinin Disease (CHAD)
Paroxysmal Cold Haemoglobinuria (PCH)
Drug induced
Allo-immune-foreign as foreign
Transfusion reactions
Haemolytic Disease of
Fetus and Newborn 
(HDFN)
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11
Q

Autoimmune Haemolytic Anaemia?

A

Autoantibodies directed against a patients own RBC’s
Usually IgG (generally warm AIHA)
or
IgM (generally cold AIHA) mediated

Warm and Cold classifications due to the behaviour of the antibodies involved and whether they react more strongly with RBC’s
at 370C or 40C
May have a mixed picture in reality

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12
Q

DAT?

A

Blood sample form a pt has ABs on RBC surface
Washed RBCs incubated with antihuman antibodies
RBC’s agglutinate-antihuman antibodies form links by binding to antibodies on RBC’s

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13
Q

Warm AIHA?

A
Usually IgG mediated: DAT +ve: 
AutoAb binds to RBCs at 37 degrees,
Removed by RE macrophages 
Part of RBC membrane lost: spherocyte
Destroyed in the spleen prematurely
Extravascular

50% idiopathic
Other associations – CLL-leukaemia, LPD-lymphoma, SLE-lupus, RA

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14
Q

Cold AIHA?

A

Usually IgM mediated: Complement + DAT
Primary CHAD
Ab binds to RBCs at 40C, causes red cell agglutination on blood film, worse in the cold (transport sample in the warm)
Associated with acrocyanosis, Raynauds, intravascular haemolysis.
Often triggered by Mycoplasma pneumonia, EBV (Secondary CHAD)
May be associated with underlying LPDs.

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15
Q

Paroxysmal cold haemoglobinuria?

A

Paroxysmal cold haemoglobinuria (PCH)
Donath-Landsteiner antibody – biphasic. Binds to RBCs at 370C and lyses them at 200C. Often triggered by viral infections.
(in exams tends to be a child playing outside, who comes in to a warm house…!)

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16
Q

management AIHA?

A
Look for associated/ underlying conditions and treat
WARM
Steroids, blood as needed
Rituximab (anti-CD20), splenectomy
COLD
Keep warm, blood warmers
Occasionally chemotherapy if LPD
17
Q

Acquired Non-IMMUNE?

A

MAHA: Microangiopathic haemolytic anaemia

Characterised by mechanical destruction (due to environment) of red blood cells and therefore fragments (schistocytes) on the blood film

Often associated thrombocytopenia
(Thrombotic Microangiopathy)

Predominantly an acquired intravascular haemolysis

18
Q

Thrombotic Thrombocytopenic purpura?

A

Rare
Text book – pentad:
1. Fever 2. Renal failure 3. Confusion
4. Thrombocytopenia 5. MAHA on blood film

Low plts, low Hb, high bili, high LDH, high creat, +/-positive troponin

Microthrombi

Often idiopathic, but also due to:
HIV, pregnancy, drugs, congenital

19
Q

Diagnosis and management?

A

Endothelial cell damage releases ultra large vWF multimers into the bloodstream which bind to vWF receptors on platelets, causing aggregation.
Reduction of ADAMTS 13 (normally proteolyses vWF multimers)
with associated IgG antibody against ADAMTS 13
ADAMTS 13 is vWF cleaving protease
Reduction leads to platelet aggregation and so cleaving of RBCs
No antibody in congenital forms: VERY RARE

Treatment
Plasma exchange, high-dose steroids, blood, folic acid
Rituximab, RRT?
Aspirin and prophylactic LMWH when platelets recover

20
Q

Hb structure?

A
2 alpha chains
&
2 beta chains
Producing
HbA (>90%) and some
HbA2 (<5%)
21
Q

SCA?

A

Caused by an abnormality in globin chain structure
They are caused by single gene disorders
The most common are the ‘Sickle Cell Diseases’
There are others such as congential dyserythropoietic anaemia (CDA)

22
Q

Thalassaemias?

A

The thalassaemias are caused by absent or reduced production of the alpha or beta globin chains which form the normal adult haemoglobin HbA (⍺2β2).
Caused by mutations in regulatory genes
Might overlap with haemoglobinopathies: HbS/beta thalassaemia

23
Q

genetics of SCC?

A

Point mutation in the beta globin gene on chromosome 11
Amino acid substitution (Adenine to thymine)
Causes glutamic acid being substituted by valine at position 6.

24
Q

Diagnosis of SCA?

A

gel electrophoresis
sickle solubility
high performance liquid chromatography

25
Q

SCA Pathophysiology?

A

deoxygenation causes polymerisation and deformation into sickle shape
vaso-occlusion causes sickle shape and infarction of downstream tissues causing death ns inflammation
reperfusion causes haemolysis
vasculopathy and endothelial dysfunction leads to release of Hb and consumption of NO leading to functional deficiency

26
Q

Effects?

A
Infarction:
Acute pain
Acute chest syndrome
Hyposplenism
Osteonecrosis (AVN)
Nephropathy

Inflammation:
Increased expression of VCAM-1 and other
adhesion molecules
Hypercoagulability

NO:
Pulmonary hypertension
Priapism
Leg ulcers
Cerebrovascular disease
27
Q

clinical effects of SCA?

A
Chronic Haemolysis and anaemia
Pulmonary Hypertension
Nephropathy (Proteinuria)
Retinopathy
AVN
Chronic Pain
Iron Overload

Mental health, psychological disorders, cognitive impairment
public health and social needs

28
Q

Emergency Events in SCA?

A

Acute Anaemia-Haemolysis, sequestration, Parvo B19 aplastic crisis
Acute Painful Crises
Acute Chest Syndromes-Hypoxaemia, chest pain, fever, infiltration
Stroke-Ischaemia or Haemorrhage
Priapism
Abdominal/ Mesenteric crises
AKI / Papillary Necrosis
Overwhelming infection-Hyposplenism, osteomyellitis (salmonella)

29
Q

management SCA?

A
EMERGENCIES
Pain relief- 30 mins
Oxygen
Antibiotics
Blood transfusions
LONG TERM
Clinic follow up
Echocardiographs
Hip examinations
Retinal screening
Urinalysis: protein
BP monitoring
Pain relief
Hydroxycarbamide-stops HbF
Blood Transfusions
30
Q

Pain Management?

A
Quick, adequate analgesia
Within 30 mins – AND review
Acute pain protocols – follow them
Believe the patient, listen to the patient
Hydration, treat trigger
VTE prophylaxis

Longer term prevention/ cure?
Hydroxyurea, Transfusion programme, Bone marrow transplant