Autoimmune Hemolytic Anemia and Drug-Related Hemolysis

Autoimmune hemolytic anemia definition

Hemolysis caused by autoantibodies against patient RBCs

Warm autoantibody definition

IgG antibody reacting at 37°C

Cold autoantibody definition

IgM antibody reacting at room temperature or colder

WAIHA mechanism

Extravascular hemolysis in spleen

Cold AIHA mechanism

Complement-mediated hemolysis

Common cold antibody specificity

Autoanti-I

Warm autoantibody specificity

Often Rh system especially anti-e

DAT use

Detects in vivo RBC sensitization with IgG or complement

A positive DAT w/ IgG suggests?

Suggests warm autoantibody

A positive DAT w/c3 suggests?

Suggests cold autoantibody

Autocontrol definition

Test of patient serum with patient RBCs

Positive autocontrol indicates what type of autoantibody?

Indicates autoantibody

Panagglutinin definition

Antibody reacting with all reagent cells

Warm AIHA screen result

Pan-reactive at AHG phase

Cold AIHA screen result

Pan-reactive at immediate spin phase

Eluate definition

Antibodies removed from patient RBCs

Warm AIHA eluate reaction result

Pan-reactive

Negative eluate definition

Suggests non-immune cause or drug effect

Adsorption definition

Removal of autoantibodies from plasma

Auto-adsorption definition

Uses patient RBCs to remove autoantibodies

Auto-adsorption time requirement

No transfusion within 3 months

Allo-adsorption definition

Uses donor cells to remove antibodies

Reason for allo-adsorption

Recent transfusion present

Purpose of adsorption

Reveal underlying alloantibodies

Hidden alloantibody risk

Can cause hemolytic transfusion reaction

#1 Cold AIHA symptom

Acrocyanosis

Cold AIHA lab finding

RBC clumping causing falsely elevated MCV

Warm AIHA symptoms

Jaundice, splenomegaly, anemia, fatigue

Lab results due to hemolysis

Increased LDH bilirubin, reticulocytes

decreased haptoglobin

Prewarm technique

Prevents cold antibody interference

RESt adsorption

Removes IgM cold antibodies especially anti-I

Drug-induced immune hemolysis definition

Hemolysis caused by drug-related antibodies

Drug-independent mechanism

Autoimmune process without drug presence in testing

What type of reaction is a methyldopa reaction?

Drug-independent DIIHA mimicking warm AIHA

Drug-dependent mechanism

Requires drug presence for reaction

Penicillin type mechanism

Drug binds RBC membrane antibody binds drug

Quinidine type mechanism

Immune complex activates complement

Penicillin testing type?

Use drug-coated RBCs

Quinidine testing type?

Drug must be present in serum

Most common drugs causing DIIHA

Cephalosporins

Positive DAT without hemolysis

Possible in drug-induced cases

Thermal amplitude

Temperature range that an antibody reacts at

Clinically significant cold antibody reacts at?

Reacts at 30°C or higher

PCH definition

Paroxysmal cold hemoglobinuria caused by anti-P

The Donath-Landsteiner test is used for what?

Confirms PCH

Warm AIHA treatment

Steroids such as prednisone

Cold AIHA trigger

Infections such as Epstein Barr virus

Pan-reactivity meaning

Reacts with all panel cells on an ABID and cannot distinguish antibody specificity

Last wash control

Ensures eluate is not contaminated with plasma antibodies