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A Haematology and Immunology > RBC: Acquired Anaemias > Flashcards

RBC: Acquired Anaemias Flashcards

1
Q

Factors influencing normal haemoglobin level

A
  • age
  • sex
  • ethnic origin
  • time of day sample taken
  • time to analysis
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2
Q

What is the normal haemoglobin level for a male 12-70?

A

140-180

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3
Q

What is the normal haemoglobin level for a male >70?

A

116-156

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4
Q

What is the normal haemoglobin level for a female 12-70?

A

120-160

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5
Q

What is the normal haemoglobin for a female >70?

A

108-143

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6
Q

What are the clinical features of anaemia?

A

General features due to reduced oxygen delivery to tissues:

  • Tiredness/pallor
  • Breathlessness
  • Swelling of ankles
  • Dizziness
  • Chest pain

Depend on age, speed of onset and Hb level

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7
Q

What features of anaemia may relate to the underlying cause?

A
  • Evidence of bleeding
    • Menorrhagia
    • Dyspepsia, PR bleeding
  • Symptoms of malabsorption
    • Diarrhoea
    • Weight loss
  • Jaundice
  • Splenomegaly/Lymphadenopathy
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8
Q

Anaemia pathophysiology

A
  • Bone marrow
    • Cellularity
    • Stroma (environment of the marrow)
    • Nutrients
  • Red cell
    • Membrane
    • Enzymes
    • Haemoglobin
  • Destruction loss
    • Blood loss
    • Haemolysis
    • Hypersplenism
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9
Q

What are red cell indices?

A

Automated measurement of red cell size and haemoglobin content

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10
Q

MCH

MCV

A

Mean cell haemoglobin

Mean cell volume (cell size)

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11
Q

What can red indices tell us?

A

A morphological description of anaemia - and a clue as to cause

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12
Q

Give 3 morphological descriptions of anaemia.

A
  • Hypochromic microcytic (pale and small)
  • Normochromic normocytic
  • Macrocytic
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13
Q

What investigation should be carried out to establish cause of hypochromic microcytic anaemia?

A
  • Serum ferritin (iron stores - for iron deficiency anaemia)
  • Distinguish between thalasaemia carriers and iron deficiency anaemia
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14
Q

What investigation should be carried out to establish cause of normochromic normocytic anaemia?

A
  • Reticulocyte count (immature red blood cells)
  • if low then problem with bone marrow.
  • if high then due to blood loss or red cell destruction
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15
Q

What investigation should be carried out to establish cause of macrocytic anaemia?

A
  • B12 and folate levels
  • Bone marrow
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16
Q

What does low serum ferritin suggest in hypochromic microcytic anaemia?

A

Iron deficiency

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17
Q

What does normal/increased serum ferritin suggest in hypochromic microcytic anaemia?

A
  • Thalassaemia
  • Secondary anaemia
  • Sideroblastic anaemia
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18
Q

Iron metabolism

A
  • Total body iron approx 4g
  • Dietary intake balanced by loss
  • Most of the body’s iron is in Hb and is recycled
  • No pathway for excretion of excess iron
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19
Q

What happens to absorbed iron?

A
  • Bound to mucosal ferritin and sloughed off OR
  • Transported across the basement membrane by ferroportin
  • Then bound to transferrin in the plasma
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20
Q

What happens to the iron absorbed in the duodenum?

A
  • Transported in plasma bound to transferrin
  • Stored in cells as ferritin
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21
Q

Which hormone reduces intestinal iron absorption?

A
  • Hepcidin is synthesised in hepatocytes in response to increased iron levles and inflammation so reduces intestinal iron absorption and mobilisation from reticuloendothelial cells
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22
Q

What is the commonest cause of anaemia worldwide?

A

Iron deficiency anaemia

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23
Q

What is normally in the history of iron deficiency anaemia?

A
  • Dyspepsia, GI bleeding
  • Other bleeding, eg menorrhagia
  • Diet (NB children and elderly)
  • Increased requirement - pregnancy
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24
Q

What can be found on examination of iron deficiency anaemia?

A

Signs of iron deficiency:

  • Koilonychia
  • Atrophic tongue
  • Angular stomatitis
  • Hypochromic microcytic red cells
  • Abdominal and rectal examination (bleeding)
25
Q

Give some examples of causes of iron deficiency.

A
  • GI blood loss
  • Menorrhagia
  • Malabsorption (can be due to gastrectomy of coeliac disease)
  • Diet
26
Q

How is iron deficiency anaemia managed?

A
  • Correct the deficiency
    • Oral iron usually sufficient
    • IV iron if intolerant of oral
    • Blood transfusion rarely indicated
  • Correct the cause
    • Diet
    • Ulcer therapy
    • Gynae interventions
    • Surgery
27
Q

What does increased reticulocyte count suggest in normochromic normocytic?

A
  • Acute blood loss
  • Haemolysis
28
Q

What does a normal or low reticulocyte count suggest in normochromic normocytic anaemia?

A
  • Secondary anaemia
  • Hypoplasia
  • Marrow infiltrate
29
Q

Give examples of underlying disease which may cause secondary anaemia

A
  • infection
  • inflammation
  • malignancy
30
Q

Blood results for secondary anaemia

A
  • 70% normochromic normocytic
  • 30% hypochromic microcytic
  • defective iron utilisation
    • increased hepcidin in inflammation
    • ferritin often elevated
31
Q

What happens in haemolytic anaemia?

A
  • Accelerated red cell destruction (↓Hb)
  • Compensation by bone marrow (↑reticulocytes)
  • Level of Hb = balance between red cell production and destruction
32
Q

What are some congenital causes of haemolytic anaemia?

A
  • Hereditary spherocytosis (HS)
  • Enzyme deficiency (G6PD deficiency)
  • Haemoglobinopathy (HbSS)
33
Q

What are some acquired causes of haemolytic anaemia?

A
  • Extravascular
    • Auto-immune haemolytic anaemia
  • Intravascular
    • Mechanical e.g. artificial valve
    • Severe infection/DIC
    • PET/HUS/TTP
34
Q

How can acquired haemolytic anaemia be subdivided?

A
  • Immune (mostly extravascular)
  • Non-immune (mostly intravascular)
35
Q

What is a direct antiglobulin test?

A

A test which detects antibody or complement on red cell membrane

Implies immune basis for haemolysis

36
Q

What does a positive DAGT suggest in haemolytic anaemia?

A

Immune mediated

37
Q

What does a negative DAGT suggest in haemolytic anaemia?

A

Non-immune mediated

38
Q

In human haemolysis of haemolytic anaemia, what does a warm-auto-antibody suggest?

A
  • Auto-immune
  • Drugs
  • CLL
39
Q

In human haemolysis of haemolytic anaemia, what does a cold auto-antibody suggest?

A
  • CAD (cold agglutinin disease)
  • Infections
  • Lymphoma
40
Q

In human haemolysis of haemolytic anaemia, what does an alloantiody suggest?

A

Transfusion reaction

41
Q

What can be seen on blood film of immune haemolysis?

A
  • Spherocytes on film
  • Agglutination in cold AIHA
42
Q

What can be seen on blood film of intravascular haemolysis?

A

Red cell fragments called schistocytes

43
Q

Tests to show if patient is haemolysing

A
  • FBC, reticulocyte count, blood film
  • Serum bilirubin (direct and indirect), LDH
  • Serum haptoglobin
44
Q

How is the mechanism of haemolytic anaemia established?

A
  • History and examination
  • Blood film
  • Direct Antiglobulin Test (Coombs’ test)
  • Urine for haemosiderin/urobilinogen
45
Q

What is the management for haemolytic anaemia?

A
  • Support marrow function
    • Folic acid
  • Correct the cause
    • Immunosuppression if autoimmune (steroids, treat the trigger)
    • Remove site of red cell destruction (splenectomy if severe)
    • Treat sepsis, leaky preosthetic valve, malignancy etc. if intravascular
  • Consider transfusion
46
Q

In macrocytic anaemia, what can results of B12 and folate assays, blood films and bone marrow tell us?

A

Differentiates between megaloblastic and non-megaloblastic anaemia

47
Q

What can cause megaloblastic macrocytic anaemia?

A
  • B12 deficiency
  • Folate deficiency
48
Q

What can cause non-megaloblastic macrocytic anaemia?

A
  • Myelodysplasia
  • Marrow infiltration
  • Drugs
49
Q

How can B12/folate deficiency present?

A
  • Anaemia
  • Neurological symptoms (subacute combined degeneration of the cord in B12 deficiency)
50
Q

What can cause B12 deficiency?

A
  • Pernicious anaemia
  • Gastric/ilieal disease
51
Q

What can cause folate deficiency?

A
  • Dietary
  • Increased requirements (haemolysis)
  • GI pathology (e.g. coeliac disease)
52
Q

Why do people have a lemon yellow tinge in megaloblastic anaemia?

A
  • Due the bilirubin and LDH
  • Red cells are friable
53
Q

How is vitamin B12 absorbed?

A
  • Dietary B12 binds to intrinsic factor, secreted by gastric parietal cells
  • B12-IF complex attaches to specific IF receptors in distal ileum
  • Vitamin B12 bound by transcobalamin II in portal circulation for transport to marrow and other tissues
54
Q

What is the commonest cause of B12 deficiency?

A

Pernicious anaemia

55
Q

What is pernicious anaemia?

A
  • An autoimmune condition where the bodies make antibodies against intrinsic factor (sometimes gastric parietal cells)
  • It results in malabsorption of dietary B12
56
Q

How long does it take for signs and symptoms of pernicious anaemia to develop?

A

1-2 years due to B12 stores

57
Q

What is the treatment for megaloblastic anaemia?

A
  • Replace vitamin B12
    • B12 intramuscular injection
    • Loading dose 3 then 3 monthly maintenance
  • Replace folate
    • Oral folate replacement
    • Ensure B12 normal if neuropathic symptoms
58
Q

What are ‘other’ causes of macrocytosis?

A
  • Alcohol
  • Drugs (Methotrexate, Antiretrovirals, hydroxycarbamide)
  • Disordered liver function
  • Hypothyroidism
  • Myelodysplasia

A Haematology and Immunology (20 decks)

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