HEMOLYTIC ANEMIAS DUE TO
OTHER INTRACORPUSCULAR
DEFECTS
What is intrinsically wrong with this RBC?
OTHER INTRACORPUSCULAR DEFECTS

Hereditary membrane defects – abnormalities in
the constituent membrane proteins or lipids may
alter the function and/or flexibility, shape, or
stability of the membrane leading to hemolysis,
most of which is extravascular via the spleen.
INTRACORPUSCULAR DEFECTS

Hereditary spherocytosis (HS)
This is a group of heterogenous disorders which
usually have an autosomal dominant inheritance
(deletion in short arm of chromosome 8).
 The specific defect is a disorder of vertical protein
interactions, most often characterized by a deficiency
of spectrin.
 The deficiency may be a primary deficiency in
spectrin or a secondary deficiency due to defective
attachment of the cytoskeleton to the lipid bilayer.
 Deficiencies in band 3, ankyrin and protein 4.2 have
also been found

MEMBRANE DEFECT IN HS
INTRACORPUSCULAR DEFECTS
The net result of the skeletal defect is increased
membrane instability and progressive membrane loss.
 This leads to a cell with a decreased surface to volume
ratio and spherocytes with decreased flexibility and
increased viscosity which all leads to extravascular
hemolysis.
 The cells may also be more permeable to sodium and
this eventually leads to decreased potassium and
water and increased cell viscosity which also
contributes to splenic culling.
 Clinical manifestations:


Jaundice, mild to severe anemia, and an enlarged spleen.
INTRACORPUSCULAR DEFECTS
May have gallstones from the increased bilirubin.
 The MCHC is increased (greater than 36%).

The peripheral smear shows spherocytes and
polychromasia
 There is increased osmotic fragility
 The autohemolysis test is positive. In this test RBCs
are incubated in their own plasma for 48 hours at 370
C and the amount of hemolysis is determined.

Normal is .2-2%.
 With hereditary spherocytosis, the hemolysis is 5-25% at
24 hours, and 75% at 48 hours.
 The hemolysis will decrease when glucose is added for
making ATP to pump out excess Na.

OSMOTIC FRAGILITY TEST
Fresh blood
Incubated blood
HEREDITARY SPHEROCYTOSIS
INTRACORPUSCULAR DEFECTS


Therapy = splenectomy
Hereditary elliptocytosis (HE)
This disease usually has an autosomal dominant
inheritance
 Several subgroups which vary in the degree of hemolysis
and clinical severity are found.
 There appears to be a spectrin dimer-dimer association
problem.
 Decreased amounts of protein 4.1 have also been found
 The defect in the membrane cytoskeleton that results
causes the abnormal shape (elliptocytes or ovalocytes).

MEMBRANE DEFECT IN HE
INTRACORPUSCULAR DEFECTS



In the heterozygote form the weakened skeleton results in cells
being permanently deformed when subjected to the sheer stress
of the microcirculation (this is transient in normal RBCs).
 The cells have a nearly normal life span.
In the homozygote state (and with some heterozygote variants)
there is severe weakening of the cytoskeleton and membrane
fragmentation occurs in addition to the formation of elliptocytes.
 This is called a hemolytic variant.
Clinical manifestations:
 For the heterozygote it is usually a mild, compensated
anemia with elliptocytes and polychromasia. The osmotic
fragility and autohemolysis tests are normal.
 In the homozygous state (rare), there is marked poikilocytosis
with elliptocytes and fragmented cells. There is increased
osmotic fragility and autohemolysis.
HEREDITARY ELLIPTOCYTOSIS
HE – HEMOLYTIC VARIANT
INTRACORPUSCULAR DEFECTS


Therapy - splenectomy in hemolytic variants
Hereditary pyropoikilocytosis (HPP)

This is a rare autosomal recessive disorder with
unstable spectrin leading to an unstable membrane
cytoskeleton that undergoes sheer stress in the
microvasculature described above for homozygous
elliptocytosis.

HPP cells actually have two spectrin defects, one from
each parent.
 There is a deficiency of alpha spectrin from one parent.
 There is a mutant spectrin that prevents selfassociation of heterodimers from the other parent
MEMBRANE DEFECT IN HPP
INTRACORPUSCULAR DEFECTS



This leads to a severe hemolytic anemia and marked
poikilocytosis with budding cells, fragments,
microspherocytes, and elliptocytes.
The cells are thermally unstable and fragment at 45-460 C,
whereas normal cells fragment at 490 C.
There is increased osmotic fragility and autohemolysis.
PYROPOIKILOCYTOSIS
HPP AFTER HEATING
INTRACORPUSCULAR DEFECTS

Disorders of membrane cation permeability

Hereditary stomatocytosis (stoma= mouth)
In this disorder the RBC is abnormally permeable to
sodium and potassium.
 The net gain of sodium is more than the net loss of
potassium.
 Therefore water rushes in and the RBCs are swollen and
less deformable and are culled in the spleen.
 The anemia may be mild to moderate with
polychromasia.
 Stomatocytes (RBCS with slit-like or mouth-like areas of
central pallor) are seen
 There is increased osmotic fragility and autohemolysis.

HEREDITARY STOMATOCYTOSIS
INTRACORPUSCULAR DEFECTS

Hereditary xerocytosis
In this disorder there is a net loss of potassium that
exceeds the net gain of sodium resulting in a dehydrated
cell as water rushes out.
 This leads to increased cytoplasmic viscosity, decreased
deformability, and culling in the spleen.
 There is decreased osmotic fragility because of the net
loss of water.


Abnormal membrane lipid composition

Spur cell anamia
This is an acquired disorder associated with severe
hepatocellular disease which causes an increases in
serum lipoproteins, leading to an excess of RBC
membrane cholesterol.
 This results in a moderate to severe hemolytic anemia
with acanthocytes, leptocytes, echinocytes, and
spherocytes.

HEREDITARY XEROCYTOSIS
SPUR CELL ANEMIA
INTRACORPUSCULAR DEFECTS


Abetalipoproteinemia (hereditary acanthocytosis)
 This is a rare autosomal recessive disorder characterized
by an absence of serum  lipoprotein, low serum
cholesterol, low triglyceride, and low phospholipid with
an increased cholesterol to phospholipid ratio.
 Acanthocytes may be seen, but there is usually no
anemia associated with this disorder.
Acquired membrane defects

Paroxysmal nocturnal hemoglobinuria
INTRACORPUSCULAR DEFECTS
This disease is characterized by an RBC membrane
that is abnormally sensitive to complement mediated
lysis (WBCs and platlets are also affected).
 There is a classic pattern of irregular intravascular
hemolysis and nocturnal hemoglobinuria.
 The condition is exacerbated during sleep when CO2
levels rise and the pH drops.
 It is believed to be caused by an abnormal clone of
stem cells (idiopathic or due to marrow damage).
 All of the cell lines lack several anchored membrane
proteins and this makes them abnormally sensitive to
the complement mediated lysis (C3b can bind).
 Lack GPI (glycophosphatidylinositol) anchoring
 protein
 This can lead to peripheral pancytopenia

PNH DEFECT
INTRACORPUSCULAR DEFECTS

Clinical findings:
The classic presentation is of hemoglobinuria in the first
morning urine specimen.
 The intravascular hemolysis that occurs during sleep
may also be triggered by infection, surgery, or drugs.
 Most patients also have hemosiderinuria.
 Abdominal and back pain and headaches occur due to
thrombosis of the abnormal platlets


Lab findings:
The peripheral smear shows pancytopenia with a
normochromic, normocytic anemia and increased
reticulocytes.
 The bone marrow is hyperplastic.
 The sucrose hemolysis and Ham's tests are positive and
there is decreased leukocyte alkaline phosphatase in the
granulocytes

INTRACORPUSCULAR DEFECTS

Treatment:
Transfusions with washed cells
 Anticoagulants for venous thrombosis

 Hereditary

enzyme deficiencies
Glucose -6-phosphate dehydrogenase
deficiency
This is the most common red cell enzyme disorder.
 The enzyme is carried on the X chromosome.
 There are many different isoenzymes, and only a few
of them have decreased enzyme activity.
 G6PD catalyzes the first step in the pentose
phosphate pathway in a coupled reaction in which
NADPH is made.
 NADPH is needed for glutathione reduction:

G6PD ACTIVITY
INTRACORPUSCULAR DEFECTS
GSH protects the hemoglobin from oxidative
denaturation to Heinz bodies.
 Normally G6PD activity is highest in young cells and
decreases as the cell ages.
 Therefore, there are no problems until the cell starts
to age.
 When a cell with an enzyme with decreased activity
ages, the net result is Heinz body formation.
 The Heinz bodies attach to the RBC membrane, and
this leads to increased membrane permeability and
rigidity and removal by the spleen.
 Under normal conditions the bone marrow can
compensate for the decreased RBC survival.

INTRACORPUSCULAR DEFECTS
However, when the individual is under acute
oxidative stress ( drugs, fava beans in some cases,
infection and being a newborn) this can result in
membrane damage and lead to acute intravascular
hemolysis.
 There is a decreased RBC count and hemoglobin,
increased reticulocytes, bite cells, hemoglobinuria,
and jaundice.
 Heinz bodies may be visualized by supravital
staining.
 Diagnosis is by demonstrating decreased enzyme
activity.
 Therapy is to avoid exposure to oxidant drugs and to
give transfusions during a hemolytic episode.

G6PD DEFICIENCY (HEINZ BODY
ANEMIA)
HEINZ BODIES
INTRACORPUSCULAR DEFECTS

Pyruvate kinase deficiency

There are many different mutants of this enzyme that is
part of the Embden-Meyerhoff pathway:
INTRACORPUSCULAR DEFECTS
Cells with PK deficiency fail to make enough ATP to
maintain normal RBC function and therefore, they have
a decreased survival time.
 Heterozygous individuals are clinically normal and
homozygous individuals have a hemolytic anemia.
 Diagnosis is by assay for enzyme function.
 On the peripheral smear, the cells are dehydrated due to
potassium loss.

PK DEFICIENCY