Auto Immune Haemolytic Anaemia Part 1 Flashcards
Define Auto Immune Haemolytic Anaemia
Premature destruction of RBCs by an autoantibody directed against individual’s own red cells
Define Elution
removal of antibodies from the sensitised red cells to identify the antibody
Describe the pathophysiology of AIHA
- Abnormality in suppressor T cell tolerance to self-antigens
- Production of antibodies against own blood group antigens
In what type of individuals is AIHA mostly common in?
- Haematological malignancy
- Individuals with other auto-immune disorders
State the two types of AIHA classifications and state what consists in each
- Classification I
a. Warm AIHA
b. Cold AIHA - Classification II
a. Drug-induced AIHA
At what temperatures do antibodies in the WAIHA and CAIHA activate in?
- WAIHA - 37 degrees
- CAIHA - 4 to 24 degrees or 30 degrees
what type of AIHA accounts for 18% AIHA
Cold AIHA
what type of AIHA accounts for 12% of AIHA
drug induced
what type of AIHA accounts for 70% of AIHA
Warm AIHA
What are the differences in pathophysiology of WAIHA, CAIHA, and Drug induced?
WAIHA - Extravascular, IgG, non complement-activating antibody
CAIHA - Intravascular, IgM, complement-activating antibody
Drug Induced - Intravascular or extravascular
Clinical symptoms of WAIHA
- Weakness, pallor
- Weight loss
- Fever
- Jaundice
- Common in children and adults
Clinical symptoms of Cold Haemolytic Disease
- Weakness, pallor
- Weight loss
- Cyanosis in extremities
- Numbness in hands and feet
- Haemoglobinuria
- Common in >50 years old
Haemotology Laboratory results of AIHA
- Anaemia
- Decreased haemoglobin and haematocrit
- Increased reticulocyte
- Macrocytosis
- Spherocytosis
- Nucleated RBC
Clinical Chemistry results of AIHA
- Increased bilirubin
- Increased lactate dehydrogenase
- low haptoglobin level
Blood bank laboratory results of AIHA
Positive DAT
What antibodies are responsible for WAIHA?
- auto anti-Rh protein
- auto anti-e,c,D,C,E,f early in disease
- auto antibodies to high incidence antigens like U in MNS
what antibodies are responsible for Cold Haemolytic Disease?
- auto anti-I
- auto anti-i
what drugs cause AIHA?
- Quinidine
- Phenacetin
- Piperacillin
- Cephalosporins
- Streptomycin
- Methyldopa
What difficulties arise by working with Warm AIHA?
- Antibody screen and panel cells are pangglutinins due to auto-antibodies hiding allo-antibodies thus allo-antibody exclusion unavailable
- DAT positive cells will immediately agglutinate via IAT
What reagent is added to DAT positive cells to make them DAT negative?
EDTA glycine acid
List the testing procedures of RBCs in WAIHA
- ABO and Rh(D)
- DAT with anti-IgG and anti-C3d separately
- Elution
- screen and panel of eluate plasma for identification of auto-antibody
- Phenotype EGA treated cells
List the test procedures of plasma in WAIHA
- ABO grouping
- Antibody screen
- Antibody panel
- Auto adsorption or allo-adsorption if patient transfused in last 3 months
- Screen and panel of adsorbed plasma for detection of allo-antibody
- IAT crossmatch on adsorbed plasma
Define Auto Adsorption
Incubation of patient RBCs against own plasma to remove autoantibodies without removing all antibodies
List the treatments for WAIHA
- High dose of corticosteroids
- Intravenous intragram
- Splenectomy
- Drugs to block antibody production
