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HEMATOLOGY > HEMOLYSIS > Flashcards

HEMOLYSIS Flashcards

1
Q

What component of hemolysis is responsible for the manifestation of jaundice ?

A
  • Bilirubin release from the red cells
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2
Q

Define hemolysis.

A
  • premature red cell destruction

avg lifespan is 120 days

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3
Q

WHy are red cells susceptible to damage?

A
  • biconcave shape to transit —-so ANY CHANGE in shape of the red cell is bad
  • limited metabolic reserve (no mitochondria; relies completely on GLUCOSE )
  • can’t generate new proteins ! Since leaving the bm)
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4
Q

Define compensated hemolysis.

A
  • incr. red cell destrcution compensated by INCR. red cell prodn (with incr. erythropoitin prodn)
  • —Hb is MAINTAINED
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5
Q

What occurs in hemolytic anemia that becomes in a decompensated state?

A
  • red cell destruct. EXCEEDING THE bone marrow CAPACITY to compensate for loss
  • –Hb FALLS
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6
Q

Consequences of hemolysis.

A
  • erthryoid hyperplasia

- excess red cell destrc. products (BILIRUBIN)

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7
Q

What is the issue with diagnosing hemolytic anaemia?

A
  • rely on DETECTING the CONSEQUENCES of hemolysis and investigating the cause
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8
Q

How does the Bone marrow respond to hemolysis?

A
  • reticulocytosis

- erythroid hyperplasia

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9
Q

Are reticulocytes nucleated cells?

Are they diagnostic of Hemolysis?

A

NO

  • –appear bluer d.t ribosomal RNA
  • —appear BIGGER than red cells

NO; just means the BONE marrow is able to RESPOND to the anemia

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10
Q

How does the blood film of a hemolytic pt look like?

A

POLYCHROMASIA (RIBOSOMAL rna)

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11
Q

How does automated reticulocyte counting occur ?

A
  • RIBOSOMAL RNA is labelled with flurochrome

- cells are COUNTED

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12
Q

How does the bone marrow appear under the miscroscope in erythroid hyperplasia? -

A

Large no.s of erythroblasts

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13
Q

What is meant by intra-vascular hemolysis? -

A

break down of the red cells IN THE blood vessels

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14
Q

Where does extravascular hemolysis occur?

A
  • at the reticuloendothelial sys. (LIVER AND SPLEEN)
  • commoner
  • HYPERPLASIA at site of the destruct.
  • release of PROTOPORPHYRIN
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15
Q

What is seen with release of protoporphyin?

A
  • unconjugated bilirubinemia
  • JAUNDICE
  • GALL stones
  • urobilinogenuria
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16
Q

What is seen in lab findings with intravascular hemolysis?

A
  1. Hemoglobinemia
  2. Methaemalbmuninaemia
  3. hemoglobinuria (PINK urine; BLACK ON STANDING )
  4. hemosiderinuria (IRON in the urine)
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17
Q

What are the causes of Intravascular hemolysis?

A
  1. ABO incompatible blood transfusion
  2. G6PD deficiency
  3. Severe falciparum malaria (Blackwater Fever)
  4. Rarer still PNH,PCH
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18
Q

What is G6PD?

A

red cell enzyme

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19
Q

What causes extravascular anemia?

A
  • all other causes of hemolysis

- less life threatening !

20
Q

How to confirm hemolytic state?

What are Haptoglobins responsible for?

A
  • FBC (+ BLOOD FILM)
  • Reticulocyte count
  • Serum unconjugated bilirubin
  • Serum haptoglobins (REDUCES; binds to free Hb)
  • Urinary urobilinogen
21
Q

What may the blood film help in identifying?

A 
Membrane damage (SPHEROCYTES) 
Mechanical damage (red cell fragm.)  
Oxidative damage (Heinz bodies) 
others (HbS)
22
Q

WHat do red cell fragments indicate?

A

vascular hemolysis

23
Q

What are special ivx for AUTOIMMUNE hemolysis?

A
  • DIRECT COOMBS’ TEST and others
24
Q

How can hemolysis be classified by?

A
  • the SITE of red cell defect .
25
Q

What are the diff. sites of red cell defects?

A
  • abnormal cell membrane
  • abnormal red cell metabolism
  • abnormal Hb
  • premature destrc. of NORMAL red cells (autoimmune
26
Q

What Abs do autoimmune hemolysis include?

A

WARM (IgG)

Cold (IgM)

27
Q

When may warm Abs be produced?

A
  • idiopathic (commonest)
  • AUTOIMMUNE d.o (SLE)
  • Drugs (penicillins at v.high doses IM- not seen )
  • Infections
  • CLL (lymphoproliferative d.o)
28
Q

When are COLD Abs produced?

A
  • infections (EBV/ mycoplasma)
    idiopathic
    lymphoproliferative d.o
29
Q

How is direct coomb’s test performed

A

identifies Abs BOUND to OWN red cell

  • patients own RBCs are mixed with a mouse Anti-human IgG—PRESENCE OF THE
30
Q

What is an ALLOIMMUNE hemolysis?

A

-“allo”= other
—-immune response to Non-self Ag from members of the SAME species
Abs produced as an IMMUNE RESPONSE!
(iMMEDIATE IgM release intravscularly)

(delayed IgG EXTRAVASCULARLY)

31
Q

When may alloimmune hemolysis occur?

A

HEMOLYTIC TRANSFUSION RXN

HEMOLYTIC DISEASE OF NEW BORN (Rh D/ ABO compatibility/ anti-Kell)

32
Q

How may MECHANICAL red cell destruct. occur?

A
  • DIC
  • Hemolytic uremic syndrome (E.coli)
  • TTP
  • LEaking Heart Valve
  • malarial infections
33
Q

What is seen the blood film on slide 36?

A
  • microspherocytes

(seen with BURNS) —-RED CELLS ARE SHEARED through DAMAGED capillaries

34
Q

When may red cell membrane defects occur?

A

VERY RARE conditions:
Liver Disease (Zieve’s Syndrome)
Vitamin E deficiency
Paroxysmal Nocturnal Haemoglobinuria

35
Q

What is seen in Zieve’s Syndrome?

A

Anaemia
Polychromatic macrocytes – reticulocytes
Irregularly contracted cells

36
Q

WHat are the clinical findings of Zieve’s Syndrome?

A
  • hemolysis
  • alcoholic liver disease
  • hyperlipidemia
37
Q

Name some example of red cell membrane abnormalities .

A

Reduced membrane deformability
Increased transit time through spleen
Oxidant environment in spleen causes extravascular red cell destruction
Hereditary Spherocytosis

38
Q

What is an example of abnormal red cell metabolism?

A
  • failure to COPE with OXIDANT stress

- failure to gen. ATP

39
Q

What is seen with G6PD def. in the blood film?

A
  • BITE CELLS

- contracted cells

40
Q

What are ex. of abnormal Hb cause of hemolytic anaemia?

A
  • sickle cell disease—shortens red cell survival !
  • –point mutation in BETA-GLOBIN chain
  • –assymptomatic if a trait
41
Q

What occurs in hereditary spherocytosis, for it to cause anaemia?

A
  • d.t inherited defects in red cell membrane skeleton—-loss of typical biconcave shape.
  • instead form non-deformable red cells, vulnerable to sequestration and destruction by the spleen
42
Q

Explain the pathophysiology of G6PD .

A
  • G6PD is required in the rate-limiting step of the hexose monophosphate shunt,in which is CONVERTS NADP to NADPH
  • NAPH is needed to generate glutathione from Oxidative glutathione! —-so low amounts of glutathione is produced
43
Q

Why is glutathione important?

A
  • important for the protecting the red cell from reactive oxygen species.
44
Q

Why does splenomegaly occur in hereditary spherocytosis?

A
  • site of spherocyte sequestration and destruction

- —d.t congestion of splenic cords (and incr. no. tissue marcophages)

45
Q

What may exacerbate hereditary spherocytosis? Why?

A

APLASTIC CRISIS!

  1. Parvovirus B19 - infects and destroys erythroblasts in the bone marrow
  2. spherocytes already have a SHORTENED life span—-incr. destruction
  3. so even a few days of decr. prodn of red cells d.t Parvovirus b19—> rapid progression of ANAEMIA within days !

HEMATOLOGY (20 decks)

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