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POM Block 2 > 14 Blood cell abnormalities > Flashcards

14 Blood cell abnormalities Flashcards

1
Q

What is anaemia?

A

A reduction in the amount of haemoglobin in a given volume of blood (reduced Hb)

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2
Q

What (apart from Hb) is reduced in anaemia?

A
  • RBC
  • Hct (hematocrit - percentage volume of RBCs)
  • PCV (packed cell volume)
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3
Q

What normally causes anaemia?

A

A reduction of the absolute amount of haemoglobin in the blood stream

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4
Q

Why can an increase in plasma volume not persist in healthy individuals?

A

The excess fluid is excreted (urine) and the plasma volumes are brought back to normal

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5
Q

What are the 4 mechanisms of anaemia?

A
  • Reduced production of RBCs/haemoglobin in bone marrow
  • Loss of blood from the body
  • Reduced survival of RBCs in circulation
  • Pooling of RBCs in a very large spleen
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6
Q

What are the probable causes of reduced synthesis of haemoglobin in the bone marrow?

A

Conditions causing

  • Reduced synthesis of haem
  • Reduced synthesis of globin
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7
Q

Namet wo causes of reduced synthesis of haem

A
  • Iron deficiency
  • Anaemia of chronic disease (chronic inflammation, Fe trapped in macrophages)
    (lead?)
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8
Q

What is the name of a condition where there is an inherited defect leading to reduced globin production?

A

Thalassaemia

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9
Q

What is the main way of determining the cause of anaemia?

A

Classification on the basis of cell size

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10
Q

What is a microcyte?

A

A red cell smaller than normal

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11
Q

What is a normocyte?

A

A normal red cell (size + Hb)

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12
Q

What is a macrocyte?

A

A red cell larger than normal

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13
Q

What does hypochromic mean?

A

A red cell with less colour than normal (less Hb)

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14
Q

What does normochromic mean?

A

Concentration of Hb within cells is normal

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15
Q

Are microcytes typically hypochromic or normochromic?

A

Hypochromic

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16
Q

What two types of cells are normochromic?

A
  • Normocytes

- Macrocytes

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17
Q

What are some common causes of microcytic anaemia?

A
  • Defect in haem synthesis

- Defect in globin synthesis (thalassaemia)

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18
Q

What are the two types of thalassaemia?

A

α and β thalassaemia

  • Defect in alpha chain synthesis
  • Defect in beta chain synthesis
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19
Q

What are the causes of iron deficiency?

A
  • Increased blood loss (commonest)
  • Insufficient intake
  • Increased requirement
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20
Q

What are some causes of increased blood loss?

A
  • Hookworm

- Menstrual (menorrhagia)

21
Q

What are some causes of insufficient intake?

A
  • Dietary e.g. vegetarians

- Malabsorption (coeliac disease, H pylori gastritis)

22
Q

What are the causes of increased requirements?

A
  • Physiological e.g. during pregnancy, infancy
23
Q

Why does macrocytic anaemia occur?

A
  • Abnormal haemopoiesis –> red cell precursors continue to produce Hb and proteins but fail to divide normally
24
Q

What are the common causes of macrocytic anaemia?

A
  • Megaloblastic erythropoiesis
  • Liver diseases/ethanol toxicity
  • Major blood loss (increased reticulocytes)
  • Haemolytic anaemia (increased reticulocytes)
25
Q

What is megaloblastic erythropoiesis?

A

A delay in maturation of the nucleus while the cytoplasm continues to mature (cell grows)

26
Q

Where are megaloblasts normally seen?

A

Bone marrow

not seen in the blood film

27
Q

What causes megaloblastic anaemia?

A
  • Deficiency of vitamin B12 or folate

- Use of drugs interfering with DNA synthesis (retarding nuclear development)

28
Q

What is the difference between polychromasia and reticulocytosis?

A

Polychromasia
- RBCs with blue tinge, young cells, newly released
Reticulocytosis
- Increased number of young cells recognised by a specific stain

29
Q

What are some causes of blood loss?

A
  • Gastrointetinal haemorrhage
  • Trauma
  • Tissue damage
30
Q

What are some causes of failed RBC production?

A
  • Early stage Fe deficiency
  • Bone marrow failure/suppression (chemotherapy)
  • Bone marrow infiltration (leukemia)
31
Q

What are some causes of pooling of RBCs in the spleen?

A
  • Hyperslenism (liver cirrhosis)

- Splenic sequestration (SCA)

32
Q

What is polycythaemia?

A

Too many red cells in circulation

33
Q

What counts are increased in polycythaemia?

A
  • Hb
  • RBC
  • Hct
34
Q

What is pseudo polycythaemia?

A

Reduced plasma volume

35
Q

What is true polycythaemia?

A

Increase in total volume of red cells in circulation

36
Q

What are the 4 mechanisms of true polycythaemia?

A
  • Blood doping/overtransfusion
  • Increased erythropoietin
  • Inappropriate erythropoietin synthesis or use
  • Polycythaemia vera (intrinsic disorder of bone marrow)
37
Q

What does polycythaemia vera cause?

A

Hyperviscosity (thick blood) leading to vascular obstruction

38
Q

How is polycythaemia vera treated?

A
  • Blood can be removed to reduce viscosity (venetriction)

- Drugs can be given to reduce bone marrow RBC production

39
Q

What is a possible cause and mechanism of a raised Hb in a patient with an abdominal mass?

A
  • Carcinoma of kidney

- Inappropriate erythropoietin synthesis

40
Q

What is a possible cause and mechanism of a raised Hb in a breathless cyanosed patient?

A
  • Hypoxia

- Appropriately increased erythropoietin

41
Q

What is a possible cause and mechanism of a raised Hb in a patient with an enlarged spleen?

A
  • Polycythaemia vera

- Abnormal bone marrow function

42
Q

What is a possible cause and mechanism of a raised Hb in a young healthy athlete?

A

Blood doping or inappropriate erythropoietin use

43
Q

Why might a person with blue lips develep polycythaemia?

A

Cyanosis –> Patient is hypoxic

44
Q

What effects can polycythaemia due to hypoxia have?

A
  • Can cause hyper-viscosity

- Predispose to thrombosis

45
Q

What is leukaemia?

A

Cancer of the blood (5% of all cancers)

46
Q

How does leukaemia occur?

A

Results from a series of mutations in a single lymphoid or myeloid stem cell

47
Q

What do mutations in lymphoid/myeloid stem cells do?

A

Lead progeny of cell to show abnormalities in proliferation, differentiation or cell survival

48
Q

slide 30

A

wahts different

POM Block 2 (9 decks)

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