Lesson 11: Extrinsic Defects Leading to Increased Erythrocyte Destruction

A type of hemolysis that occurs within the blood vessel.

Intravascular

A type of hemolysis where RBCs are destroyed outside the blood vessels and removed by spleen.

Extravascular

A type of Extrinsic defect which does not involve the antibodies.

Non - Immune

A type of extrinsic defect that occurs due to the presence of antibodies attacking the RBCs.

Immune

It is a normocytic, normochromic anemia, and all are acquired disorders that causes an accelerated RBC destruction with **reticulocytosis**.

Extrinsic Immune Defects

It is a normocytic, normochromic anemia, and all are acquired disorders that cause an intravascular hemolysis with **schistocytes**.

Extrinsic Non - Immune Defects

Most commonly encountered autoimmune hemolytic anemia, wherein RBCs are coated with **IgG/complement** causing membrane loss and spherocytes. Antibodies will also react at 37C.

Warm Autoimmune Hemolytic Anemia or WAIHA

What are the possible antibodies of WAIHA?

IgG, IgA, IgM

True or False: WAIHA is neither idiopathic or secondary.

False

RBCs are coated by **IgM and complement**. It is secondary to ***M. pneumoniae****,* infectious mononucleosis, and other viral infections.

Cold Autoimmune Hemolytic Anemia or Cold Agglutinin Disease

What antibody is present in CAD?

anti - I

It is most commonly seen in young children after a viral respiratory infection. This disorder is caused by **IgG biphasic Donath - Landsteiner Antibody** with Anti - P.

Paroxysmal Cold Hemoglobinuria

What is the positive result for Donath - Landsteiner Test?

Hemolysis

In Biphasic, the anti - P will __ complement to RBC in the cold or less than 20C (answer fix or lyse)

Fix

In Biphasic, RBC will __ when warmed at 37C (answer fix or lyse)

Lyse

It is where the recipient has IgM antibodies against the donor cells.

Hemolytic Transfusion Reaction

This occurs within minutes to hours and common cause is ABO incompatibility.

Acute HTR

This occurs days to weeks, and common cause is alloantibodies against Duffy and Kidd blood group.

Delayed HTR

It occurs when an IgG alloantibody produced by the mother crosses the placenta and binds to fetal RBCs.

Hemolytic Disease of the Newborn

What are the other blood groups that causes hemolytic disease of the newborn?

K, c, Fy^3

What is the common cause of Hemolytic Disease of the Newborn?

ABO incompatibility

It is a formation of blood clots that block the blood vessels, giving them a small spaces.

Microangiopathic Hemolytic Anemia or MAHA

It is a deficiency of the enzyme ADAMSTS13.

Thrombotic Thrombocytopenic Purpura

An enzyme that prevents spontaneous platelet activation and clot formation and break down UlvWF.

ADAMSTS13

A bacterial infection caused by *E. coli* and *Shigella* among children.

Hemolytic Uremic Syndrome or HUS

It occurs in pregnant women, particularly with eclampsia. This disorder is a hemolysis/hemolytic anemia.

HELLP Syndrome

What does HELLP Syndrome stands for?

Hemolysis Elevated Liver Enzymes Low Platelet count Syndrome

It occurs when there is a larger space within blood vessels.

Macroangiopathic Hemolytic Anemia

It occurs after the body has forceful contact with hard surfaces like marathon runners and tennis players.

March Hemoglobinuria or Exercise - Induced Hemoglobinuria

Complete the following (Answer if mechanical trauma, infectious agents, and thermal burns)

\[ Format: 1.) thermal burns; 2.) mechanical trauma; 3.) infectious agents \]

1\.) mechanical trauma; 2.) infectious agents; 3.) thermal burns

Enumerate the other causes of macroangiopathic anemia:

(Format: mmmm tttt, iiii aaaa, dddd and cccc, vvvv, tttt bbbb)

Mechanical trauma, infectious agents, drugs and chemicals, venoms, thermal burns