Haemolytic anaemia

Question 1

Define haemolytic anaemia

Answer 1

Increased peripheral destruction of RBCs

Bone marrow continues to produce cells

Increased consumption means BM has to work harder to compensate.

Question 2

Describe the investigation- what are the components of a haemolysis screen

Answer 2

FBC: Normocytic anaemia

Blood film: Spherocytes or red cell fragments

Reticulocytes: Increased

LDH: Increased (due to cell turnover)

Bilirubin: Increased (unconjugated)

Haptoglobin: Decreased in intravascular haemolysis

DAT: Positive in some immune cases

Question 3

3 examples of inherited haemolytic anaemias (non-immune)

Answer 3

SCD
Membrane disorders e.g. hereditary spherocytosis
G6PD deficiency

Question 4

3 examples of acquired haemolytic anaemia (non-immune)

Answer 4

paroxysmal nocturnal haemoglobinuria

DIC

valve haemolysis

Question 5

example of acquired haemolytic anaemia (immune)

Answer 5

AI- warm, cold, drug induced

alloimmune- transfusion reaction, HDN

Question 6

What is haptoglobin

Answer 6

Haptoglobin- protein mopped up by free haemoglobin- destroyed RBC= lots of free Hb= decreased haptoglobin

Question 7

difference in test results between intravascular and extravascular haemolysis

Answer 7

Intravascular- low haptoglobin, haemoglobinuria, haemoglobinaemia, hemosiderinuria

Extravascular- N haptoglobin, no haemoglobinuria, no haemoglobinaemia, no hemosiderinuria

Question 8

3 types of auto-immune acquired haemolytic anaemia

Answer 8

warm
cold
drug induced

Question 9

Mx of warm AIAH

Answer 9

steroids, bloods as necessarr, rituximab, splenectomy

Question 10

what is autoimmune haemolytic anaemia?

Answer 10

autoantibodies directed against a patients own RBCs- usually IgG in warm and IgM in cold mediated.

Question 11

What is the direct antiglobin test/ Coombs test?

Answer 11

blood sample from patient is incubated with antihuman antibodies (Coombs reagent). RBCs agglutinate bc the antihuman abs form links with the human abs on the RBCs.

Question 12

Is warm AIAH DAT +?

Answer 12

Yes

Question 13

Is warm AIAH DAT +?

Answer 13

Yes

Question 14

2 triggers for cold AIAH

Answer 14

EBV, Mycoplasma pneumonia

Question 15

Mx of cold AIAH

Answer 15

keep warm, blood warmers, occasionally chemo

Question 16

What is MAHA?

Answer 16

microangiopathic haemolytic anaemia

Question 17

characteristics of MAHA

Answer 17

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

Question 18

clinical px of TTP (thrombotic thrombocytopenic purpura)

Answer 18

fever
renal failure
confusion
thrombocytopenia
MAHA on blood film
microthrombi 
low plt, Hb
high bili, LDH, creatinine
\+troponin

Question 19

5 causes of TTP

Answer 19

idiopathic
HIV
pregnancy 
drugs 
congenital

Question 20

what does TTP stand for?

Answer 20

thrombotic thrombocytopenic purpura

Question 21

Pathogenesis of TTP

Answer 21

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= low plt levels

Question 22

Tx for TTP

Answer 22

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

Question 23

Normal adult Hb chains

Answer 23

2 alpha, 2 beta

Question 24

Pathogenesis of SCA

Answer 24

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

Question 25

Screening for SCA

Answer 25

heel prick at day 8 gel elctrophoresis sickle solubility

Question 26

Describe the pathophysiology of SCD

Answer 26

sickle shape leads to vaso-occlusion and infarction resulting in downstream tissue death and inflammation Irreversible sickling leads to haemolysis This leads to release of Hb and consumption of NO leading to a functional deficiency.

Question 27

5 symptoms of SCD

Answer 27

``` acute pain acute chest syndrome hyposplenism nephropathy inflammation pulm HT priapism leg ulcers cerebrovascular disease retinopathy ```

Question 28

emergency events in SCD

Answer 28

``` acute anaemia acute painful crises acute chest syndromes- hypoxaemia, chest pain, fever, infiltration stroke priapism abdominal/mesenteric crises AKI papillary necrosis overwhelming infection ```

Question 29

emergency events in SCD

Answer 29

``` acute anaemia acute painful crises acute chest syndromes- hypoxaemia, chest pain, fever, infiltration stroke priapism abdominal/mesenteric crises AKI papillary necrosis overwhelming infection ```

Question 30

4 emergency mx of SCD

Answer 30

Pain relief within 30mins Oxygen Antibiotics Blood transfusions

Question 31

9 aspects of long term SCD care

Answer 31

``` Clinic follow up Echocardiographs Hip examinations Retinal screening Urinalysis: protein BP monitoring Pain relief Hydroxycarbamide Blood Transfusions ```