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Clinical Pathology > Common causes of anaemia and thrombocytopenia > Flashcards

Common causes of anaemia and thrombocytopenia Flashcards

1
Q

What are the possible causes of anaemia?

A
  • Haematinic deficiencies
  • Secondary to ‘chronic disease’
  • Haemolysis
  • Alcohol, drugs, toxins
  • Renal impairment - EPO
  • Primary haematological / marrow disease (Malignant
    Haemoglobin disorders (sickle etc), Aplasia, Congenital)
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2
Q

What are the three different classes of anaemia?

A

Macrocytic
Normocytic
Microcytic

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3
Q

What are the possible causes of macrocytic anaemia?

A
  • B12, Folate, metabolic (e.g. thyroid/liver disease)
  • Marrow damage (booze, drugs, marrow diseases)
  • Haemolysis (due to reticulocytosis)
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4
Q

What are the possible causes of normocytic anaemia?

A
  • Anaemia of chronic disease/inflammatory
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5
Q

What are the possible causes of microcytic anaemia?

A
  • Iron deficiency
  • Haemoglobin disorders
  • (sometimes chronic disease)
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6
Q

Does the human body excrete iron?

A

No

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7
Q

Where in the gut is iron absorbed?

A

Duodenum (less in jejunum)

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8
Q

What percentage of the body’s RDI of iron is absorbed?

A

7%

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9
Q

How does the body obtain most of it’s RDI of iron?

A

It recycles it

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10
Q

What transports iron across the gut mucosa?

A

Transferrin

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11
Q

Where is iron stored?

A

Ferritin/haemosiderin

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12
Q

What are the dietary sources of iron?

A
  • red meat
  • chicken contains some iron
  • baked beans
  • boiled eggs
  • canned sardines or other oily fish and mussels
  • breakfast cereals with added vitamins
  • green leafy vegetables
  • dried fruit
  • wholemeal bread
  • lentils, beans and peas
  • nuts
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13
Q

What lab tests are performed in suspected anaemia?

A
  • FBC, indices and film
  • Ferritin
  • %hypochromic cells
  • Serum iron / TIBC
  • Marrow
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14
Q

What are the features of microcytic anaemia (i.e. MCV vs MCH)

A

MCV - low

MCH - low

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15
Q

What are the main causes of microcytic anaemia?

A
  • Blood loss from anywhere: gut / PV / PU / respiratory tract etc
  • Increased demand: pregnancy / growth
  • Reduced intake: diet / malabsorption
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16
Q

What are the main causes of microcytic anaemia in children?

A
  • Diet
  • Growth
  • Malabsorption
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17
Q

What are the main causes of microcytic anaemia in women?

A
  • Menstrual loss / problems
  • Pregnancy - don’t underestimate the potential for long term deficiency after this
  • Diet
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18
Q

What are the main causes of microcytic anaemia in older people?

A 
Bleeding
GI problems:
- ulcer / gastritis / aspirin
- malignancy
- Diverticulitis
- GI surgery of various types
- lots of others
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19
Q

What are the various forms of iron therapy that are in use?

A
  • Oral iron - Often unreliable
  • IM iron - painful – out of date
  • IV iron - increasingly used
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20
Q

What causes the classic cell morphology seen in megaloblastic anaemia?

A

Impaired DNA synthesis

21
Q

What is the difference between megaloblastic and macrocytic cells?

A
  • Megaloblasts are RBCs in bone marrow smear
  • Macrocytes in the peripheral blood.
  • Folate and B12 deficiency cause megaloblastic-macrocytosis but macrocytes can form in peripheral blood without prior megaloblasts in the bone marrow (nonmegaloblastic macrocytosis) as can occur from alcoholic damage of RBCs (not associated with lack of folate or B12)
22
Q

How does a deficiency in B12 of folate cause anaemia?

A
  • DNA consists of purine/pyrimidine bases
  • folates are required for their synthesis
  • B12 is essential for cell folate generation
  • So low Folate or B12 starves DNA of bases
23
Q

Where is intrinsic factor secreted?

A

Gastric parietal cells

24
Q

What is the function of intrinsic factor?

A

Facilitates the uptake of B12

25
Q

Where in the gut is intrinsic factor absorbed?

A

Receptors in terminal ileum

26
Q

What are the possible causes of B12 deficiency?

A

Nutritional - vegans

Gastric problems

  • Pernicious anaemia (autoimmune)
  • gastrectomy

Small bowel problems

  • Terminal ileal resection / Crohns
  • stagnant loops / jejunal diverticulosis
  • tropical sprue / Fish tapeworm
27
Q

How many months of folic acid does the body store?

A

4

28
Q

Where is folic acid absorbed?

A

Upper small bowel

29
Q

What are the main sources of folic acid?

A

Mainly green vegetables, beans, peas, nuts and liver

30
Q

What are the main causes of folic acid deficiency?

A
  • Mainly dietary / malnutrition
  • Malabsorption / small bowel disease
  • Increased usage: (pregnany, haemolysis,
    inflammatory disorders)
  • Drugs / alcohol / ITU
31
Q

What are the features common to B12 or folate deficiency?

A
  • Megaloblastic anaemia
  • Can have pancytopenia if more severe
  • Mild jaundice
  • Glossitis / angular stomatitis
  • anorexia / wt loss
  • sterility
32
Q

What are the lab features of B12 and folate deficiency?

A
  • Blood count and film - marrow sometimes
  • Bilirubin and LDH - ‘haemolysis’
  • B12 and folate levels
  • Antibodies
  • B12 absorption tests +/- IF
  • GI investigations:(Crohn’s, malabsorption, blind loop etc)
33
Q

What is the classic cause of B12 deficiency?

A

Pernicious anaemia

34
Q

What is pernicious anaemia?

A
  • Abs to parietal cells / intrinsic factor
  • Autoimmune associations
  • Atrophic gastritis with achlorhydria
  • Increased incidence of Ca stomach
35
Q

What is subacute combined degeneration of the cord?

A
  • Demyelination of dorsal + lateral columns
  • Commonly caused by B12 deficiency
  • Peripheral nerve damage
  • Presents as:
    • Peripheral neuropathy / Paraesthesiae
    • Numbness and distal weakness
    • Unsteady walking
    • Dementia
36
Q

What is the treatment for for B12 deficiency?

A
  • B12 + Folate until B12 deficiency excluded
  • B12 x5 then 3 monthly for life for PA
  • Folic acid 5mg daily to build stores
  • ?need for potassium and iron initially
  • Response: retics by day 7, blood count / MCV
    neuropathy…..many months for full effect
37
Q

What are the possible causes of haemolysis?

A

Inside

  • Haemoglobinopathy (Sickle cell)
  • Enzyme defects (G6PD)

Membrane
- Hereditary Spherocytosis / elliptocytosis

External

  • Antibodies (warm / cold)
  • Drugs, toxins
  • Heart valves
  • Vascular / vasculitis / ‘microangiopathy’
38
Q

What tests are required in suspected haemolysis?

A
  • Anaemic (or not – compensated)
  • High MCV, macrocytic
  • High Reticulocytes
  • Blood film (fragments / spherocytes)
  • Raised bilirubin, LDH (lactate dehydrogenase)
  • Low haptoglobins
  • Urinary Haemosiderin
39
Q

What are the features of anaemia of chronic disease?

A
  • A common general medical issue
    • Malignant / inflammatory / infectious
    • Multiple medical diseases (DM, autoimune etc)
  • Typically normal MCV
  • Reduced red cell production due to :
  • Abnormal iron metabolism, poor erythropoetin response and blunted marrow response.
40
Q

What is hepcidin?

A

A key regulator of the entry of iron into the circulation in mammals.

41
Q

What is the relevance of hepcidin in chronic disease?

A

In states in which the hepcidin level is abnormally high such as inflammation, serum iron falls due to iron trapping within macrophages and liver cells and decreased gut iron absorption. This typically leads to anemia due to an inadequate amount of serum iron being available for developing red cells.

42
Q

What are the features of anaemia of chronic disease

A
  • No other causes of anaemia
  • A suitable medical history
  • Usually mild anaemia, normal MCV
  • Often raised inflammatory markers
  • ESR, CRP, PV etc
  • Normal/high ferritin + low serum iron
  • Normal % Saturation transferrin
43
Q

What are the common causes of thrombocytopenia?

A
  • Drugs, alcohol, toxins
  • ITP (sometimes associated with lymphoma/CLL/HIV)
  • Other autoimmune diseases
  • Liver disease and / or hypersplenism
  • Pregnancy (physiological and a range of complications)
  • Haematological / marrow diseases
  • Infections acute or otherwise e.g. Acute sepsis / HIV / other viral infections (EBV and many others)
  • Disseminated Intravascular Coagulation (DIC)
  • Range of congenital conditions
44
Q

What is immune thrombocytopenia purpura?

A
  • Isolated low platelet count with normal bone marrow and the absence of other causes of thrombocytopenia.
  • Common – distinguish kids + adults
  • An immune disorder
  • Occurs on its own or as part of other diseases: Lymphomas/CLL, HIV, other autoimmune
  • Can be acute /chronic / relapsing
45
Q

What is the presentation of immune thrombocytopenia purpura?

A
  • Bruising or petechiae or bleeding
  • Platelet count can be anything:
  • -
46
Q

What is the treatment for immune thrombocytopenia purpura?

A
  • Steroid remains first line ?schedule
  • IV immunoglobulin
  • Other immunosuppressives or splenectomy are common next options
  • Newer thrombo-mimetics now have a place
    • Eltrombopag
    • Romiplostin
  • These have thrombopoetin – like properties and are getting more widely used
47
Q

What is thrombotic thrombocytopenia purpura?

A

Extensive microscopic clots to form in the small blood vessels throughout the body. These small blood clots, called thrombi, can damage many organs including the kidneys, heart and brain.

48
Q

What are the clinical features of thrombotic thrombocytopenia purpura?

A

Suspect if thrombocytopenia and:

  • Fever
  • Neurological symptoms
  • Haemolysis (retics / LDH)
  • Seek evidence of microangiopathy
49
Q

What is the treatment for thrombotic thrombocytopenia purpura?

A
  • Plasma exchange with FFP/plasma
  • Steroids
  • (Vincristine)
  • (Rituximab)

Clinical Pathology (65 decks)

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