Chapter 20 Intro to increased destruction of Erythrocytes (Hemolysis)

define hemolysis

increased rate of destruction/lysis of RBCs resulting in a shortened lifespan

what are some clinical findings caused by hemolysis

reduced tissue oxygenation → increased erythropoietin production in kidneys

bone marrow accelerates RBC production → reticulocytosis

what are some findings in intravascular hemolysis (in veins)

MET hemoglobinemia

MET hemoglobinuria

decreased serum haptoglobin/absent serum haptoglobin

schistocytes

this RBC morphology is commonly seen in intravascular hemolysis

schistocytes

what are some findings of extravascular hemolysis (in spleen)

increased serum unconjugated bilirubin

what is the difference between a hemolytic disorder and a hemolytic anemia

disorder = RBCs are destroyed but bone marrow can compensate

anemia = bone marrow is unable to compensate for the shortened survival of RBCs

a condition where increased destruction of RBCs occurs and the bone marrow is able to compensate is called

hemolytic disorder

what is fragmentation (intravascular) hemolysis

trauma to the RBC that causes a breech and allows cell contents to spill into the plasma

• 10-20% of normal RBC destruction

what are the 3 mechanisms that salvage/protect RBCs from oxidizing during fragmentation hemolysis

• Hgb binds to haptoglobin

• Metheme binds to hemopexin

• metheme binds to albumin

define macrophage-mediated hemolysis

hemolysis of RBCs from macrophages due to defective surface markers

• can be senescent or pathological

• mainly in spleen, liver, and bone marrow

if a RBC is partially digested, it can form a ________?

spherocyte

increased amounts of macrophage-mediated hemolysis would result in _______ unconjugated bilirubin and urobilinogen levels

increased

in fragmentation hemolysis:

• serum

  • haptoglobin is ?

  • free Hgb is ?

  • hemopexin is ?

• urine

  • urobilinogen is ?

  • free Hgb is ?

  • methemoglobin is ?

  • prussian blue staining of urine sediment is ?

• what morphology is commonly present

haptoglobin is decreased

free Hgb is increased

hemopexin is decreased

urobilinogen is increased

free Hgb is positive

methemoglobin is positive

prussian blue staining of urine sediment is positive

schistocytes

in macrophage-mediated hemolysis:

• serum

  • haptoglobin is ?

  • free Hgb is ?

  • hemopexin is ?

• urine

  • urobilinogen is ?

  • free Hgb is ?

  • methemoglobin is ?

  • prussian blue staining of urine sediment is ?

• what morphology is commonly present

haptoglobin is decreased

free Hgb is increased

hemopexin is decreased

urobilinogen is increased

free Hgb is negative

methemoglobin is negative

prussian blue staining of urine sediment is negative

spherocytes

this RBC form is commonly seen in macrophage-mediated hemolysis

spherocytes

describe the process of protoporphyrin catabolism

1. Old or damaged RBC hemolyzes (via macrophage or fragmentation) into Hgb

2. Hgb is broken into heme & polypeptides

3. heme is broken down into protoporphyrin & iron

4. protoporphyrin is catabolized inside macrophage into unconjugated bilirubin & urobilinogen

5. unconjugated bilirubin & urobilinogen are processed in the liver then moved to intestine

6. products are excreted in stool

the metabolites of protoporphyrin are processed by

the liver

if the 3 salvage mechanisms are overloaded, what happens to metheme and methemoglobin?

it gets filtered into the urine

during salvage, metheme binds with hemopexin; however, if hemopexin is exhausted, metheme can bind temporarily with ?

albumin

the bilirubin metabolism and iron salvage systems are designed to handle a loss of ___ RBC per day.

1%

pathological hemolysis is a loss of > ____ of RBC per day

1%

what is it called when the presence of methemoglobin, methealbumin, and hemopexin-heme gives plasma a coffee-brown color?

icterus

what could cause icterus in plasma

increased hemolysis

what is the most commonly used laboratory test to identify accelerated erythropoiesis?

reticulocyte count

• think bone marrow is working hard to spit out increased RBC

what are some laboratory test results that can indicate hemolytic anemia

• increased retic count

• elevated serum indirect bilirubin level with a normal serum direct bilirubin level

• moderate to marked decrease in serum haptoglobin (fragmentation hemolysis)

a rapidly dropping hemoglobin from acute hemolytic anemia is differentiated from acute hemorrhage or hemodilution by

presence of schistocytes in peripheral smear

what RBC morphology is not associated with a type of hemolytic anemia

target cells

serum haptoglobin _____ quickly in intravascular hemolysis and ___ in extravascular hemolysis

decreased; remains constant

Which is a cause of extravascular hemolysis?

• RBC is lysed in the macrophage.

• WBC is lysed in the macrophage.

• Macrophages do not recognize RBCs.

• RBC is lysed in the macrophage.

RBC is lysed in the macrophage.

The presence of hemoglobinuria, hemosiderinuria, and hemoglobinemia indicate that hemolysis is:

intravascular

Which is decreased in intravascular hemolysis?

haptoglobin

The reticulocyte count is the most commonly used test to identify:

accelerated erythropoiesis

All of the following are seen in the various types of hemolytic anemia EXCEPT

• hypochromia

• schisoctyes

• polychromasia

• Hereditary Spherocytosis

hypochromia

Which red blood cell morphology is associated with extravascular hemolysis?

spherocytes

The term hemolytic disorder in general refers to a disorder in which there is:

Excessive loss of RBCs from the body

RBC destruction that occurs when macrophages ingest and destroy RBCs is termed:

macrophage-mediated

Which of the following is a potential cause of fragmentation hemolysis

• Malaria

• increased haptoglobin

• excessive exercise

• mitral valve prolapse

malaria