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Yr 3 Haem > haemolytic anaemia > Flashcards

haemolytic anaemia Flashcards

1
Q

definition of haemolytic anaemia

A

Premature erythrocyte breakdown causing shortened erythrocyte life span (<120 days) and anaemia

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2
Q

classifications of causes of haemolytic anaemia

A

hereditory

  • membrane defecys
  • metabolic defects
  • haemoglobinopathies

acquired

  • autoimmune
  • isoimmune
  • drugs
  • trauma
  • infection
  • paroxysmal nocturnal haemoglobinuria
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3
Q

hereditory membrane defects = haemolytic anaemia

A

hereditory spherocytosis

elliptocytosis (elliptical erythrocytes)

hereditory ovalocytosis

hereditory stomatocytosis

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4
Q

hereditory spherocytosis

A

autosomal dominant

coombs -ve

prevalence 1:3000

low spectrin (structural membrane protein) = low deformability of spherical erythrocytes

= trapped in spleen

= extravascular haemolysis

signs - splenomegaly and jaundice

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5
Q

hereditory metabolic causes of haemolytic anaemia

A

ie enzyme defects

  • G6PD deficiency
  • pyruvate kinase deficiency - autosomal recessive
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6
Q

G6PD deficiency

A

X linked

affects 100million mainly men in Mediterranean, Africa, middle/far east

G6PD is important in maintaining glutathione in reduced state.

most asymptomatic

Deficiency results in susceptibility to oxidative stress (e.g. precipitated by sulphonamides, nitrofurantoin, primaquine, aspirin, dapsone, vicia faba - fava beans/favism, illness).

in severe oxidative attacks = rapid anaemia and jaundice

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7
Q

hereditory haemoglobinopathies that = haemolytic anaemia

A

sickle cell disease

thalassaemia

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8
Q

acquired autoimmune causes of haemolytic anaemia

A

warm or cold Ab attach to erythrocytes = intravascular and extravascular haemolysis

Warm’ antibodies (IgG) agglutinate erythrocytes at 37 ̊C.

  • Associated with SLE, lymphomas or methyldopa.

‘Cold’ antibodies (IgM) agglutinate erythrocytes in at room temperature or colder.

  • Associated with infections (e.g. Mycoplasma, EBV) or lymphomas.
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9
Q

isoimmune causes of haemolytic anaemia

A

transfusion reaction

haemolytic disease of the newborn

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10
Q

drug causes of haemolytic anaemia

A

penicillin

quinine (through formation of drug–antibody–erythrocyte complex).

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11
Q

trauma causes of haemolytic anaemia

A

microangiopathic haemolytic anaemia caused by red cell fragmentation in abormal microcirculation eg:

  • haemolytic uraemic syndrome,
  • TTP
  • DIC,
  • malignant hypertension,
  • pre-eclampsia and eclampsia
  • artificial heart valves

= intravascular haemolysis and schistocytes

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12
Q

infection causes of haemolytic anaemia

A

malaria - RBC lysis and blackwater fever (haemoglobinuria)

sepsis

all infections can exacerbate haemolysis

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13
Q

paroxysmal nocturnal haemoglobinuria

A

increased complement-mediated lysis caused by reduced synthesis of protein cellular anchor of complement degrading proteins

rare acquired stem cell disorder, with haemolysis (especially at night -> haemoglobinuria), marrow failure and thrombophilia

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14
Q

epidemiology of haemolytic anaemia

A

common

Genetic causes are prevalent in African, Mediterranean, Middle Eastern populations.

Hereditary spherocytosis is the most common inherited haemolytic anaemia in northern Europe.

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15
Q

sx of haemolytic anaemia

A

jaundice

haematuria, dark urine

anaemia

ask about: systemic illness, FHx Dx, travel Hx, race

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16
Q

signs of haemolytic anaemia

A

pallor - anaemia

jaundice

hepatosplenomegaly

pigmented gallstones due to bigh BR from haemolysis

leg ulcers - poor blood flow

17
Q

Ix for haemolytic anaemia

A

blood

blood film

urine

direct antiglobin Coombs test (DAT)

Osmotic fragility test or Spectrin mutation analysis - to identify membrane abnormalities.

Ham’s test

Hb electrophoresis or enzyme assays - when other causes excluded

bone marrow biopsy (rarely required) - erythroid hyperplasia

18
Q

blood results for haemolytic anaemia

A

FBC - low Hb and haptoglobin, high reticulocytes, MCV and unconjugated BR

UE

folate

19
Q

haptoglobin

A

mop for free Hb

lowers in intravascular haemolysis

20
Q

blood film in haemolytic anaemia

A

leucoerythroblastic picture

macrocytosis

nucleated erythrocytes or reticulocytes,

polychromasia

spherocytes - hereditory spherocytosis or autoimmune haemolytic anaemia

elliptocytes - hereditory eliptocytosis

sickle cells - SCD

hypochromic microcytic anaemia - thalassaemia

fragmented erythrocytes (schistocytes) - MAHA

malarial parasites,

erythrocyte Heinz bodies (denatured Hb, stained with methyl violet seen in G6PD deficiency).

abnormal cells in malignancy

21
Q

urine results in haemolytic anaemia

A

raised urobilirubin

If intravascular haemolysis = haemoglobinuria, haemsiderinuria

22
Q

direct coombs’ test

A

identifies erythrocyte coated with antibodies (agglutins) or complement using antihuman globulin

warm agglutin and cold agglutin

indicates immune cause

23
Q

Ham’s test

A

lysis of erythrocytes in acidified serum in paroxysmal nocturnal haemoglobinuria

More recently – red cells are analyzed, using monoclonal antibodies to the GPI-anchored proteins (CD55 and CD59) and flow cytometry.

24
Q

haemolytic anaemia summary

A

may be normocytic

if a lot of young RBC and reticulocytes = macrocytic

suspect if

  • reticulocytosis >2% of RBCs. or reticulocyte count >100x10(9)/L
  • mild macrocytosis
  • low haptoglobin
  • high BR
  • high LDH
  • high urobilinogen

often mild jaundice (pre-hepatic, so no BR in urine)

25
Q

aetiology of haemolytic anaemia

A

haemolysis is the premature breakdown of RBCs before 120days

occurs in circulation - intravascular

or in reticuloendothelial system (macrophages of liver, spleen and marrow) - extravascular

in sickle cell anaemia - lifespan may be 5days

can be asymptomatic

if marrow doesnt compensate enough = haemolytic anaemia

26
Q

questions when you suspect haemolytic anaemia

A

is there red cell breakdown

is there increased red cell production

is the haemolysis extra- or intravascular

why is there haemolysis

27
Q

things showing increased red cell break down

A

anaemia - normo/macrocytic

high unconjugated BR

high urinary urobilinogen

high serum LDH - released from red cells

28
Q

things showing there is increased red cell production

A

high reticulocytes = high MCV

polychromasia

29
Q

features of extravascular haemolysis

A

splenic hypertrophy

splenomegaly

30
Q

features of intravascular haemolysis

A

high free plasma Hb - released from red cells

methaemalbuminaemia - some free Hb is broken down in the circulation to produce haem and globin - haem combines with albumin = mathaemalbumin

low plasma haptoglobin - mops up free Hb, then removed by liver

haemoglobinuria - red-brown urine, absence of RBC

haemosiderinuria

31
Q

haemosiderinuria

A

occurs when haptoglobin binding capacity is exceeded

= free Hb to be filtered by the renal glomeruli, absorption of free Hb via renal tubules and storage in tubular cells as haemosiderin

detected in urine as sloughed tubular cells by prussian blue staining approx 1wk after onset - implies chronic intravascular haemolysis

32
Q

acquired Coombs test positive haemolytic anaemia

A

drug induced

autoimmune haemolytic anaemia

paroxysmal cold haemoglobinuria

isoimmune - acute transfusion reaction, haemolysis of the newborn

33
Q

Coombs -ve acquired causes of autoimmune haemolytic anaemia

A

autoimmune hepatitis

hep B and C

post flu and other vaccinations

drugs - piperacillin, rituximab

34
Q

Ix results for paroxysmal nocturnal haemoglobinuria

A

urinary haemosiderin +ve

if suspect in coombs -ve intravascular haemolysis seek confirmation by flow cytometry

35
Q

Ix results for G6PD deficiency

A

film - bite and blister cells, heinz bodies

enzyme assay (>8wks post crisis as young RBC may hav eenough enzyme so results normal)

(figures 8.31 and 32)

36
Q

pyruvate kinase deficiency

A

autosomal recessive

low ATP production = low RBC surviavl

homozygotes have neonatal jaundice

later haemolysis with splenomegaly +- jaundice

Ix - enzyme assay

37
Q

Ix for hereditory spherocytosis

A

mild if Hb >110g/L and reticulocytes <6%

high BR = gallstones

osmotic fragility tests - RBC show increased fragility in hypotonic solutions

38
Q

hereditory eliptocytosis

A

coombs -ve

autosomal dominant

asymptomatic - somewhat protects from malaria

some people have worse phenotype and death in utero

Yr 3 Haem (16 decks)

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