Autoimmune Haemolytic Anemia

Question 1

what is a test used to detect hemolityc anemias?

why is this test used?

Answer 1

Coombs test or DAT (Direct Antiglobulin Test) test is essential

Patient with autoimmune hemolytic anemias have warm-reactive antibodies of IgG isotype in their red cells

Question 2

what characterizes autoimmune hemolytic anemias?

Answer 2

1) shortened RBC survival
2) presence of autoantibodies directed against autologus red cells

Question 3

warm antibody type is for which antibody?

in what diseases can it be used?

Answer 3

IgG

SLE, CLL

Question 4

Cold agglutinin antibody type is for which antibody?

in what acute diseases can it be used?

in what chronic diseases can it be used?

Answer 4

IgM

Mycoplasma or mononucleosis infection

lymphoplasmacytic lymphoma

Question 5

cold hemolysin antibody type is for which antibody?

in what diseases can it be used?

Answer 5

IgG

in children after viral infection

Question 6

Warm antibody type is IgG that has high affinity to what?

what is characterisitc of it?

what can it do with complement?

it can lead to what?

what secondary causes may lead to warm antibody type?

what is the pathogenesis of Warm antibodies type IgG?

Answer 6

human RBC

it is the most common type of warm antibody

it can allow complement to bind

can lead to extravascular hemolysis

SLE, CLL, Penicillin, alpha-methyl dopa

• the patient’s RBCs typically are coated with IgG autoantibodies with or without complement proteins they
• get trapped by macrophages in spleen and Kupffer cells in the liver
• hemolysis is extravascular IgG coated red cells bind to Fc receptors on macrophages which will remove red cell membrane during partial phagocytosis
• red cell become spherocytic
• following loss of membrane these red cells are then broken down in spleen

Question 7

what is the most common cause of cold agglutinin type?

what other infection can cause it?

what is the pathogenesis?

what symptom may be seen?

Answer 7

Mycoplasma pneumoniae infection

EBV, CMV, Influenza, HIV

• IgM Ab binds to red cells and fixes complement at low temperatures
• when the IgM/C3b-coated RBC circulates to warmer tissues, the IgM dissociates, leaving complement C3b on the original RBC
• remember C3b is an excellent opsonin, which the leads to removal of affected red cells by phagocytes in spleen, liver, and bone marrow
• in infections, this is usually transient and self-limited

Raynaud’s phenomenon may be seen

Question 8

General Labs for Autoimmune Hemolytic Anemia

Hb

Reticulocytes

Peripheral Blood Smear

Serum Bilirubin

Hemoglobinuria

Haptoglobin

Coombs test

Answer 8

Hb = reduced

Reticulocytes = increased

Peripheral Blood Smear = polychromatophils, nucleated cell

extravascular = spherocytes

intravascular = schistocytes

Serum Bilirubin = raised

Hemoglobinuria = intravascular

Haptoglobin = reduced

Coombs test = positive

Question 9

What can be said about the RBC?

Answer 9

they look spherocytic

Question 10

what type of autoimmune hemolytic anemia is this?

Answer 10

cold agglutinin type

Question 11

What type of Coombs test is the most used?

Answer 11

direct coombs test

Question 12

what does a Coomb test detect?

what is added to the patient’s RBC?

how do you know the RBC’s are coated with IgG or complement?

Answer 12

presence of antibody or complement coated red cells

compliment or anti-IgG

when they agglutinate

Question 13

what does an Indirect Coombs test work?

what is mixed with the patients RBC’s?

how do you know if there are antibodies agains the patient’s RBC’s?

Answer 13

detects the presence of antibodies in patient’s serum

IgG and test red cells get mixed with patients serum

agglutination

Question 14

What are microangiopathic hemolytic anemias?

are these extravacular or intravascular hemolytic anemias?

what can cause this type of hemolytic anemia?

Answer 14

mechanical hemolytic anemias

or

RBC are damaged by contact with endothelium and fibrin

this is a type of intravascular hemolytic anemia

causes:

1) platelet thrombi
2) fibrin thrombi
3) aortic stenosis

Question 15

what are 2 examples of platelet thrombi causing diseases?

what about fibrin thrombi causing diseases?

Answer 15

Platelet thrombi:

1) hemolytic uremic syndrome
2) thrombotic thrombocytopenic purpura

Fibrin thrombi:

1. disseminated intravascular coagulation
2. HLLP syndrome (helomytic elevated transaminases, low platelets, associated with preeclampsia)

Question 16

what are the labs found in microangiopathic hemolytic anemia?

what do you see in the peripheral smear?

Answer 16

normocytic anemia

hemoglobinuria

hemosidenuria

schistocytes present in peripheral blood smear

Question 17

what is this?

Answer 17

schistocytes

Question 18

what is the pathogenesis of Rh incopatibility?

What is the major cause of Rh incompatibility?

risk of developing antibodies will increase with what?

Answer 18

• mother has RBC with antibodies (IgG) which go from the placenta into the fetus, destroying its RBC’s.
• Rh (D antigen) negative mother gets immunized by Rh antigen when mother becomes pregnant with Rh positive fetus (immunization either from previous pregnancy/blood transfusion)

D antigen

subsequent pregnancies (if anti-D immunoglobulin prophylaxis is not given)

Question 19

what are the clinical features of Rh incompatibility?

Answer 19

• hemolytic anemia
• unconjugated hyperbilirubinemia
• risk of developing kernicterus
• unconjugated bilirubin is normally bound to albumin
• liver function is impaired
• albumin synthesis may be reduced
• this increases the risk of kernicterus

Question 20

what is hemolytic disease of the newborn?

on what blood group infants does this disease happen?

Answer 20

its a ABO incompatibility where hemolysis occurs by non-complement mediated phagocytosis of IgG coated red cells

occurs almost exclusively in infants with blood group A or B who are born to group O mothers (only those who have presence of anti-A & anti-B IgG type antibodies)