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Haematology > Microcytic Hypochromic Anaemia > Flashcards

Microcytic Hypochromic Anaemia Flashcards

1
Q

what is the definition of microcytic hypochromic anaemia?

A

low Hb
low MCV <0.8
hypochromic = low uptake of stain

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2
Q

the causes of microcytic. hypochromic anaemia are associated with what?

A

reduced haemoglobin production

causes smaller cells and less uptake of stain

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3
Q

what causes are due to problems producing the haem group?

A

iron deficiency anaemia

anaemia of chronic disease

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4
Q

what causes are due to problems producing the porphyrin ring?

A

sideroblastic anaemia

lead poisoning (cabot rings)

pyridoxine responsive anaemia

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5
Q

what causes are due to problems producing the globin chains?

A

thalassemia

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6
Q

how does iron deficiency anaemia develop?

A

due to there being insufficient iron to produce haemoglobin

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7
Q

what are common causes of low iron?

A

chronic blood loss = menorrhagia, GI bleeds

malabsorption = coeliac disease, post gastrectomy

poor dietary intake = vegan or vegetarian

infection = hookworm

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8
Q

what are specific signs of iron deficiency anaemia?

A

nails = koilonychias

mouth = angular stomatitis, atrophic glossitis

throat = post cricoid webs, plummer vinson syndrome in PM women

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9
Q

what investigation results would indicate iron deficiency anaemia?

A

FBC = low Hb / reticulocytes

iron studies = low iron, low ferritin and low transferrin saturation

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10
Q

what does ferritin levels indicate?

A

iron stores

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11
Q

what does transferrin levels indicate?

A

transported iron

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12
Q

what iron replacement should be given in iron deficiency anaemia?

A

200mg ferrous sulphate or fumerate

should be given for minimum of 3 months

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13
Q

what are the common side effects of iron replacement?

A

nausea
black stool
diarrhoea
constipation

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14
Q

if response to iron replacement is not adequate, what should you consider?

A

poor compliance
wrong diagnosis
continued activity of underlying cause

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15
Q

in iron deficiency anaemia, when should you refer for further investigation (OGD +/- colonoscopy)?

A 
iron deficiency anaemia with dyspepsia 
all men with unexplained IDA
IDA with rectal bleeding 
all women not menstruating with unexplained IDA
not responding to treatment
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16
Q

what is the name of rare type of anaemia that can be an X linked condition or secondary to chemotherapy or anti TB drugs and lead poisoning?

A

sideroblastic anaemia

*ineffective erythropoiesis will drive iron absorption and deposition in organs other than liver

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17
Q

when should sideroblastic anaemia be considered?

A

microcytic hypochromic anaemias not responding to treatment

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18
Q

what is shown in investigations in sideroblastic anaemia?

A

marrow biopsy = ring sideroblasts

microcytic anaemia with high iron, ferritin and transferrin

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19
Q

how is sideroblastic anaemia treated?

A

treat underlying cause and regular blood transfusions

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20
Q

what is thalassemia?

A

a group of conditions in which there is defective production of the globin chains found in haemoglobin - normal chains, not enough of them!

this defective production results in accumulation of unbalanced haemoglobin chains in RBC - leads to cells being small and hypochromic and susceptible to premature haemolysis

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21
Q

in general, what populations are thalassemias more common in?

A

african, asian and southern european populations

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22
Q

briefly describe the genetics behind alpha thalassemia?

A

there are four a globin genes on chromosome 16

a thalassemia is caused by deletion mutation in any of these genes

due to alpha globin being present in all haemoglobin subtypes, the production of all types of Hb will be affected

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23
Q

what occurs in a thalassemia trait?

A

one or two alpha genes missing

24
Q

what is the characteristics of a thalassemia trait?

A

asymptomatic carrier state, no treatment needed

microcytic, hypochromic red cells with mild anaemia

25
Q

how can a thalassaemia trait be distinguished from iron deficiency?

A

ferritin will be normal

26
Q

what happens in HbH disease?

A

three copies of the a gene are lost so the production of normal haemoglobin is significantly reduced

this results in increased production of abnormal haemoglobin (HbH)

27
Q

what are the symptoms of HbH disease?

A

general anaemia symptoms

symptoms of chronic haemolysis = jaundice, leg ulcers, hepatosplenomegaly

(other = growth retardation, gallstones, iron overload)

28
Q

what does HbH look like on FBC, iron studies and film?

A

FBC = low Hb, MCV and MCH

Iron = normal or increased iron / ferritin

film = heinz bodies, target cells

29
Q

what is diagnostic of HbH?

A

HPLC - high performance liquid chromatography

  • low HbA, HbA2 and HbF
  • high HBH
30
Q

how is HbH treated?

A

folic acid supplementation - to support increased erythropoiesis

mild - intermittent transfusion

severe - regular transfusions +/- splenectomy

31
Q

what is Hb barts hydrops fetalis?

A

all 4 copies of a gene are mutated

as a result of no functional alpha haemoglobin, the only type is Hb Barts

results in hydrops fetalis and IUD

32
Q

briefly describe the genetics behind B thalassemia?

A

B thalassemia develops due to point mutation in beta globin gene on chromosome 11

this can result in either reduced (B+) or absent (B0) production of B globin

due to B chain only being present in HbA, there will be reduced HbA production and a compensatory increase in production of other types of haemoglobin

33
Q

what is B thalassemia trait and what are the clinical features?

A

the trait is found when patients are heterozygous for the mutation (one normal copy)

asymptomatic

34
Q

what is the biochemical features of B thalassemia trait?

A

FBC: mild microcytic, hypochromic anaemia

HPLC: raised HbA2 diagnostic

35
Q

what is B thalassemia intermedia?

A

the less severe form of clinically apparent B thalassemia

36
Q

how does B thalassemia intermedia present?

A

mild to moderate anaemia +/- splenomegaly

37
Q

how is B thalassemia intermedia managed?

A

not usually very symptomatic

may require intermittent transfusions

38
Q

how does b thalassemia major occur?

A

patient is homozygous for B0 (absent B chains)

39
Q

when and how does B thalassemia major normally present?

A

usually within first year of life

failure to thrive
severe anaemia
extra medullary haematopoiesis: hepatosplenomegaly, skull bossing, multiple organ damage

40
Q

what does FBC, iron studies and blood film show in B thalassemia major?

A

FBC = low Hb and MCV

iron studies = normal

film = target cells, nucleated RBCs (normally not nucleated)

41
Q

what does HPLC show in B thalassemia major?

A

very high HbF
high HbA2
low HbA

42
Q

what is shown on skull XR in B thalassemia major?

A

hair on end sign

43
Q

how is B thalassemia major managed?

A

life long transfusions

folate supplementation

life long transfusions + iron chelators (deferiprone)

+/- splenectomy

44
Q

what is the main mortality of B thalassemia major?

A

iron overload

45
Q

what are the consequences of iron overload?

A

endocrine dysfunction = impaired growth and pubertal development, diabetes, osteoporosis

cardiac disease = cardiomyopathy, arrhythmias

liver disease = cirrhosis, hepatocellular cancer

46
Q

how is iron overload prevented?

A

use iron chelating drugs (bind to iron which is then excreted)

47
Q

what are other consequences of life long transfusions (except iron overload)?

A

viral infection = HIV, hep B and C

alloantibodies = hard to crossmatch

transfusion reactions

increased risk of sepsis (bacteria like iron)

48
Q

give an example of the normal production of abnormal globin chains?

A

variant haemoglobin eg HbS

49
Q

how does sickle cell trait (HbAS) occur?

A

one normal, one abnormal B gene

50
Q

what are the features of sickle cell trait (HbAS)?

A

asymptomatic carrier state

may sickle in severe hypoxia eg high altitude, under anaesthesia

blood film normal

mainly HbA, HbS <50%

51
Q

how does sickle cell anaemia (HbSS) occur?

A

two abnormal genes

52
Q

what type of haemoglobin predominates in HbSS?

A

HbS >80%, there is no HbA

53
Q

what is a sickle crises?

A

episode of tissue infarction due to vascular occlusion - symptoms depend on site and severity and pain may be extremely severe

54
Q

what can precipitate a sickle cell crises?

A 
hypoxia 
dehydration 
infection 
cold exposure 
stress / fatigue
55
Q

how is sickle cell crises treated?

A 
opiate analgesia 
hydration 
rest 
oxygen 
antibiotics if infection 
red cell exchange transfusion in severe crises eg chest crisis or stroke
56
Q

other than sickle cell crises, what are the other consequences of HbSS?

A

chronic haemolysis = shortened RBC lifespan

sequestration of sickled RBCs in liver and spleen

hyposplenism due to repeated splenic infarcts

57
Q

how is HbSS managed long term?

A

hyposplenism - reduce risk of infection by prophylactic penicillin and vaccinations

folic acid supplementation

hydroxycarbamide to reduce severity of disease

regular transfusion in select cases

Haematology (11 decks)

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