hemolytic-anemia.pptx......,.. by Keerthi

Keerthi.k
B.sc,MLT – 3rd
year
Hemolytic anemia

Normal Red Blood Cell
 Discoid shape with 7-8 micron diameter
 Can squeeze thru 3 micron capillary
 As it ages, it loses water & surface area,
impairing deformability
 These changes are detected by the RES and
trigger removal of the aged RBCs by
macrophages

Anemia
 Initial evaluation: MCV
 If MCV >100: megaloblastic or not?
 If MCV <80: iron deficient or not?
 MCV 80-100: reticulocytosis or not?
– Increased retics: Hemolysis or posthemorrhage
– Decreased retics: Renal dz, liver dz,
hypothyroid, anemia of chronic dz,
myelodysplasia, leukemia, myeloma, etc.

Hemolytic Anemia
 Inadequate number of RBCs caused by
premature destruction of RBCs
 Severity depends on rate of destruction and
the marrow capacity to increase erythroid
production.

Classification of Hemolytic Anemia
 Site of RBC destruction-Extravascular or
Intravascular
 Cause of destruction- extracorpuscular
(abnormal elements in vascular bed that
“attack” RBCs) or intracorpuscular (erythrocyte
defects- membrane abnormalities, metabolic
disturbances, disorders of hemoglobin)

Pathways of RBC Destruction
 Extravascular: RBCs phagocytized by RE cells;
RBC membrane broken down; Hemoglobin broken
into bilirubin (conjugation and excretion by liver),
and iron (binds to transferrin, returns to marrow)
 Intravascular: Free hemoglobin binds to
haptoglobin or hemopexin or is converted to
methemalbumin. These proteins are cleared by the
liver where the heme is broken down to recover
iron & produce bilirubin.

Hemolytic Anemias
 Intrinsic RBC causes
– Membranopathies: hereditary spherocytosis
– Enzymopathies: G6PD
– Hemoglobinopathies: Sickle cell disease
 Extrinsic causes
– Immune mediated: Autoimmune (drug, virus, lymphoid
malignance) vs Alloimmune (transfusion reaction)
– Microangiopathic (TTP)
– Infection (Malaria)
– Chemical agents (spider venom)

Acute Intravascular Hemolysis
 Causes: Blood transfusion, thermal burns, snake
bites, infections (clostridia, malaria, Bartonella,
Mycoplasma), mechanical heart valves, PNH
 Hemoglobinemia- pink or red plasma
 Hemoglobinuria: brown or red after spinning down
RBCs
 Urine hemosiderin: urine hemoglobin reabsorbed
by renal tubular cells; detect by staining sediment
 Low haptoglobin: binds free hemoglobin
 Methemalbumin: appears after depletion of
haptoglobin

Acute Extravascular Hemolysis
 Sudden fall in hemoglobin level with no
evidence of bleeding or intravascular
hemolysis (no hemoglobinemia or
hemoglobinuria)
 Clinical setting usually points to cause

Causes of Extravascular Hemolysis
 Bacterial & Viral infections
 Drug- induced
 Autoimmune
 Hemoglobinopathies
 Membrane Structural Defects
 “Environmental” Disorders- Malignancy
associated DIC, TTP, Eclampsia

Infectious causes of hemolysis
 5-20% of pts with falciparum malaria have
acute intravascular hemolysis (black water
fever); most have mild extravascular hemolysis
 Clostridial sepsis may cause severe
intravascular hemolysis
 Mild hemolysis occurs with mycoplasma
pneumonia; often associated with high titer
cold agglutinin; self limited

Drug-induced Hemolysis
 May occur by an immune mechanism or by
challenging the RBC metabolic machinery
 Oxidant drugs causing hemolysis in G6PD
deficiency: nitrofurantoin, sulfa drugs, dapsone,
primaquine, pyridium, doxorubicin
 Drugs causing immune-mediated hemolysis:
penicillin, quinidine, methyldopa, streptomycin

G6PD Deficiency
 ~10% of African-American males have X-linked
A variant
 The older RBCs are lost from circulation
 New RBCs have normal or high G6PD levels;
therefore they can usually compensate for the
hemolysis even if the drug is continued

Drug Induced Hemolysis
 Formation of antibodies specific to the drug: in
high doses PCN binds RBC membrane, if pt forms
Ab against PCN, the RBC are destroyed
 Induction of Ab to RBC membrane
antigens:methyldopa induces autoab to Rh ag
 Selective binding of streptomycin to RBC
membrane with formation of complement fixing
antibody
 All have Coombs (DAT) positive for IgG

Autoimmune Hemolytic Anemia
 Anticipate this cause of hemolysis in infections,
collagen vascular diseases, lymphoid malignancies
 Generally, acute extravascular hemolysis
 Spherocytes seen; no fragments; elevated LDH;
suppressed haptoglobin; reticulocytes
 Autoantibodies are directed against RBC
components (eg, Kell antigen)
 May be warm-reacting (IgG) or cold-reacting (IgM)
antibody

Causes of Autoimmune Hemolysis
 SLE
 Non-Hodgkins lymphomas, CLL
 Hodgkins Disease
 Myeloma
 HIV
 Hepatitis C
 Chronic Ulcerative Colitis

Diagnosis of Hemolysis
 Symptoms depend on degree of anemia (ie, rate of
destruction)
 Clinical features: anemia, jaundice, reticulocytosis,
high MCV & RDW, elevated indirect bili, elevated
LDH, low haptoglobin, positive DAT (AIHA)
 Acute intravascular hemolysis: fever, chills, low
back pain, hemoglobinuria
 Smear: polychromatophilia, spherocytosis &
autoagglutination

Management of Hemolysis
 The increase in RBC production requires
adequate iron (intravascular hemolysis) &
folate supplies (all hemolytic states)
 Intravascular hemolysis- transfusion reaction-
stop transfusion, IVFs to induce diuresis and
mannitol (increases renal blood flow &
decreases hemoglobin reabsorption)

hemolytic-anemia.pptx......,.. by Keerthi

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