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Flashcards in Anaemia I Deck (37)
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1

Define anaemia. 

Hb level below normal. 

2

What are 'normal' Hb levels affected by?

Age

Sex

Pregnancy

Altitude

3

Effects of anaemia

A slightly depressed Hb level may be asymptomatic (Hb 70-100 g/L)

More severe or impaired cardiorespiratory system 

  • Tiredness
  • Palpitations
  • Short of breath
  • Angina
  • Cardiac failure

4

What determines the Hb level?

The Hb level is a balance between:

  • Production of RBC in bone marrow, which needs:
    • Normal blood forming cells
    • Haematinics and hormones (EPO)
    • Absence of inhibitors (inflammatory cytokines)
  • Shortened time of RBC in circulation
    • Blood loss from circulation: haemorrhage
    • Shortened RBC life span: haemolysis

A change in level of Hb can either be a failure of production or increased breadown or loss

5

Reticulocyte count

  • Measure of recently produced RBC (1-2 days old)
  • Measure of marrow erythropoietic activity.
    • Increased = healthy marrow response to anaemia
    • Reduced/low-normal = ?marrow (production) pathology

6

Haematinics

Iron studies

B12 and folate

7

Tests for haemolysis

Bilirubin, haptoglobin, LDH

Measure of increased RBC breakdown. 

8

Bone marrow aspirate and trephine

Assesses marrow activity, function +/- presence of abnormal cells

Aspirate

  • Cellular details
  • Iron stores

Trephine

  • Overall view of BM structure
  • Better assessment of cellularity
  • Patchy abnormalities e.g. lymphoma

9

Classification of anaemias

Decreased production (synthetic failure) vs. increased destruction/loss (bleeding, haemolysis...)

or

MCV (mean corpuscular volume of RBC)

  • Microcytic = 'too small'
  • Normocytic = 'just right'
  • Macrocytic = 'too big'

10

Microcytic anaemic causes

  • Iron deficiency
  • Anaemia of chronic disease (ACD)
  • Thalassaemias/haemoglobinopathies
  • Others
    • Congenital sideroblastic anaemia (rare)
    • Lead poisoning

11

Microcytic anaemia common features

Failure of adequate Hb incorporation into RBC. 

Iron deficiency: lack of iron for haem. 

ACD: block of iron transfer into RBC

Thalassaemia/haemoglobinopathies: problem with production of globin chain for Hb molecule. 

12

Anaemic of chronic disease

  • May be microcytic of normocytic. 
  • Also may be hypochromic or normochromic. 

Irons stores fail to incorporate iron into RBC. 

  • BM resistant to EPO
  • Inadequate production of EPO in response to anaemia

Not helped by iron therapy (can have mixed Fe deficiency and ACD). 

Treat underlying cause + EPO may help. 

Iron findings

  • Transferrin low: production inhibited in inflammation, acute phase response. 
  • Serum ferritin high: increased body iron stores, increased in inflammation (acute phase)
  • BM iron increased: increased iron in macrophages.

Causes

  • infection
  • Inflammatory disorders: rheumatoid, SLE etc
  • Malignancy

13

Iron studies in iron deficiency

Never look at serum iron.

Ferritin reduced = iron deficiency

Ferritin normal/low-normal = ?iron defiency

  • Acute phase response
  • Look at transferrin saturation (if reduced - iron deficiency is likely)

14

Causes of iron deficiency

Blood loss

  • Iron deficiency in an adult Australian is bowel cancer until proven otherwise

Dietary

  • Vegetarians/vegans
  • Infants (cow milk protein/lactose intolerance), adolescents
  • Pregnancy (increased requirement)
  • Menorrhagia/increased requirement
  • Elderly

Malabsorption

  • Coeliac disease
  • Crohn's 

15

Causes of macrocytic anaemia

Magaloblastic

  • B12, folate, medication (folate depletion - e.g. MTX), BM disorders. 

Non-megaloblastic

  • Increased reticulocyte count e.g. acute bleed or haemolysis
  • Normal reticulocyte count
    • Liver disease/alcohol
    • Hypothyroidism
    • Bone marrow disorders

Spurious

  • E.g. Myeloma 

16

Blood film findings in megaloblasic anaemia

  • Single/pancytopenia
  • Macrocytosis +/- oval macrocytes
  • Hypersegmented neutrophils

17

Vitamin B12 deficiency causes

Dietary

  • Rarely except strict vegans

Malabsorption

  • Lack of instrinsic factor
    • Pernicious anaemia
    • Gastrectomy
  • Intrinsic factor present
    • Terminal Ileal disease (IBD) or resection

Metabolic causes (rare)

18

Effects of B12 deficiency

Dividing cells and neurological

  • Megaloblastic anaemia
  • Gastrointestinal effects
  • Neurological
    • Peripheral neuropathy
    • Subacute combined degeneration of cord
    • Other (delirium screen)

19

Haemoglobinopathies

Thalassaemia

Haemoglobin variants

20

Thalassaemia

Decreased rate of production of one of the globin chains, causing an 'imbalance' and therefore red cell changes. 

Alpha thalassaemia: decreased production of alpha globin chains

Beta thalassaemia: decreased production of beta globin chains

21

Haemoglobin variants

Production of Hb with an abnormal globin chain e.g. HbS

Most common is sickle cell disease

Amino acid substitution in globin chain. 

22

Alpha thalassaemia

Number of alpha genes deleted

  • One or two: alpha thal trait (asymptomatic)
  • Three: Hb H disease (mild to moderate disease) 
  • Four: hydrops fetalis (incompatible with life) 

23

Homozygous alpha thalassaemia

Hydrops fetalis

4 alpha globin genes deleted. 

Cannot make HbF, HbA or HbA2

Severe anaemia

Fatal pre-term

24

Beta thalassaemias

Decreased production of beta globin chain

Homozygous: severe disease

Heterozygous: asympotmatic, microcytic RBC

25

Homozygous beta thalassaemia

Marked decrease in HbA (decreased beta globin chains, excess alpha globin chains).

Symptoms from age 3-6 months (HbF)

Severe anaemia plus:

  • Erythroid hyperplasia ++ and bony malformations
  • Hepatosplenomegaly
  • Iron overload
    • Cardiomyopathy, endocrine disorders etc. 

Transfusion dependent for life

26

Haemoglobin E

Substitution one amino acid in beta globin chain. 

Common in South East Asia.

HbE homozygous and heterozygous

  • Asymptomatic
  • Low MCV and blood film changes only

Double heterozygote HbE + beta thal

  • Severe disease (like beta thal major)

27

Haemoglobin S

Substitution one amino acid in beta globin chain.

HbS less soluble and precipitates in hypoxia (sickling)

Heterozygous HbS (sickle cell trait)

  • Asymptomatic with normal FBC and film

Homozygous HbS (sickle cell anaemia)

  • Severe disease
  • Anaemia, sickle cell crises with pain and vascular occlusion by sickling cells

28

Bone marrow failure syndromes

Aplasia: decrease in haemopoietic cells

Dysplasia: BM cells abnormal

Bone marrow infiltration: BM replacement

29

Anaemia due to aplasia

General BM failure

  • Aplastic anaemia
  • Pancytopenia - low Hb, WBC and platelets

Specific to RBC

  • Pure red cell aplasia - parvovirus, autoimmune

30

Bone marrow dysplasia

Bone marro wnromal or increased cellularity but cells look abnormal and are dysfunction. 

Primary myelodysplastic syndromes

  • Acquired bone marrow genetic change
  • Often high MCV and low WBC and/or platelets

Secondary

  • Medication, pyridoxine deficiency, heavy metal poisoning