Hemolytic Anemias: Extracorpuscular Defects (Chapter 14)

Immune hemolysis

Results from antibodies, complement, or both attatching to the RBC membrane

Diagnosis of immune hemolysis is confirmed by:

A positive direct antiglobulin test (DAT, aka, Coombs test)

Complement

A group of serum proteins that interact with each other to bring about, complete-dependent cell lysis

Immune hemolytic anemia

Patient that produces antibodies to foreign red cell antigens

What can cause autoimmune hemolytic anemia to occur?

• Transfusions

• Pregnancy

• Organ transplantation

Acute hemolytic transfusion reactions (acute HTRs)

Acute intravascular hemolysis that is associated with ABO blood group antibodies

Delayed hemolytic transfusion reactions (delayed HTR)

Associated with antibodies to blood groups other than ABO

Hemolytic disease of the fetus and newborn (HDFN)

Fetal or neonatal red cells are destroyed by maternal antibodies

What causes hemolytic disease of the fetus and newborn?

Maternal-fetal blood group incompatibility

Autoimmune Hemolytic Anemia

Antibodies directed against the patient’s own RBC

Paroxysmal cold hemoglobinuria (PCH)

• Not common, representing only 1-7% of patients

• Most common in children who had experienced viral disorders

Drug-induced hemolytic anemia

Patients produce antibodies directed at a particular drug, its metabolites, or red cells coated with the drug. These antibodies then destroy the red cells

How may species of malaria can infect humans?

Four

P. falciparum

The most severe species of malaria that causes severe disease with often fatal outcomes

Late stages of Plasmodium vivax malaria produce these, what are they called?

Schüffner’s dots

Babesia

Zoonotic parasitic infection that is usually tickborne but can also be transmitted through blood transfusions

Babesiosis can be distinguish from malaria by formation of these, what are they?

Tetrads of merozoites (Maltese crosses)

Bartonellosis

Caused by any Bartonella bacteria

What are the two primary methods of transmission for Bartonella bacteria?

• Sand fly (Bartonella bacilliformis, Carrion’s disease)

• Cat (Bartonella henselae “cat scratch fever”)

Hemolytic phase of Bartonellosis

Anemia may be severe; blood smear show many nucleated RBCs and reticulocytosis

Patients in the hemolytic phase of bartonellosis can be effectively treated with:

Antibiotic therapy

Tumor phase of Bartonellosis (aka, verruca peruviana)

Second stage

• Verrucous nodes (warty tumors) on face & extremities

Clostridium perfringens

Gram-positive, spore-forming bacillus that is responsible for the development of gas gangrene

What is the preferred locations of clostridium perfringens?

Deep tissues where anaerobic conditions are ideal for the organism

What can occur if a patient has Clostridium perfringens present in deep tissue

• Tissue damage from the release of enzymes and toxins

• Hemolysis often severe, with hemoglobinemia & hemoglobinuria

Microangiopathic hemolytic anemia (MAHA)

Group of disorders characterized by fragmentation of the red cells as they pass through small, abnormal arterioles (intravascular hemolysis)