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Haematology week 1 > Normal erythropoiesis > Flashcards

Normal erythropoiesis Flashcards

1
Q

Define anaemia

A
  • Uni defines it as reduced total red cell mass
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2
Q

What are the 2 initial blood results which indicate anaemia ?

A

Hb concentration and haematocrit

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3
Q

What does anaemia result in ?

A

Insufficienct Hb to supply the cells

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4
Q

What are the levels of Hb in males and females with indicate anaemia ?

A
  • Males - Hb < 130g/L
  • Females - Hb <120g/L
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5
Q

Does having a low Hb concentration or haematocrit always mean you have anaemia ?

A

No they are surrogate markers i.e. often correlates to anaemia but not always,

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6
Q

What is the normal range of haematocrit for males and females ?

A
  • Males; 0.38-0.52 i.e. 38-52%
  • Females; 0.37-0.47 i.e. 37-47%
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7
Q

How is Hb concentration measured ?

A

Obv need to take a blood sample for both

For Hb concentration is then measured using a spectrophotometric method where the red cells are burst to create a Hb solution and then the Hb is stablised (cyan-metHb)‏, the optical density i.e. how red the solution is, is measured at 540nm

The optial density is proportional to the conc of Hb known as beers law

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8
Q

What is the law which states that The optial density is proportional to the conc of Hb ?

A

Beers law

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9
Q

Define what haematocrit is

A

It is the ratio or percentage of whole blood which is red blood cells

Hct of 0.5 = 50% of the total blood is red blood cells

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10
Q

Define Hb concentration

A

This is the amount of hemoglobin in a volume of blood (so its the Hb concentration in the total blood not specifically the red blood cells)

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11
Q

Why is Hb conc and Hct possibly not a good measure of anaemia in acute blood loss ?

A
  1. If someone has a rapid loss of blood, say 50% of total blood for this example, the Hb concentration and Hct of the blood still in the person would be normal
  2. Its only when plasma expansion occurs from body compensating (and possible recieving fluids) do you see the Hb conc and Hct decrease
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12
Q

Why may Hb conc or Hct not be a good measure of anaemia in someone where haemodilution has occured i.e. in pregnancy or just been given fluids ?

A

because they have a normal red blood cell mass its just the plasma volume is increased beyond normal and ==> made the results look like anaemia

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13
Q

What is the physiological response to anaemia ?

A
  • Increase red cell production
  • Commonly see reticulocytosis (increase in recticulocytes) - a small portion of recticulocytes in the bone marrow may produce a quick response to increase erythrocytes numbers (slightly) rapidly, but the main up-regulation of recticulocytes takes 2-3days
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14
Q

What are the characterisitic features of recticulocytes pointing out the ones which differentiate them from erythrocytes ?

A
  • Red cells that have just left the bone marrow
  • Larger than average red cells
  • Still have remnants of protein making machinery (RNA)‏ which causes them to stain purple/deeper red as a consequence
  • Blood film appears ‘polychromatic’ - more than one colour
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15
Q

Using automated analysers what red cell indicies is there and what do they tell us ?

A
  • The haemoglobin concentration (Hb) - this is the concentration of Hb in the blood
  • The number of red cells (concentration)‏
  • The size of the red cells. (Mean Cell Volume or MCV)‏
  • Haematocrit (Hct) - the ratio/% of red blood cell in the blood
  • Mean cell haemoglobin (MCH) - the average mass of hemoglobin per red blood cell in a sample of blood
  • Mean cell haemoglobin concentration (dont really remember this one)
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16
Q

Other than using the automated analysers what other tests can we do ?

A
  1. Blood film - look at cellular morphology
  2. Reticulocyte count - assess marrow response
  3. Additional tests - Depending on clinical details and lab findings
17
Q

What are the 2 ways in which we classify anaemia ?

A
  1. Based on pathophysiology
  2. or morphological characteristics - this is the way it is classified along with measuring haemoglobin content
18
Q

Which of the 2 ways of classifying anaemia is used in the practical classification of anaemia ?

A

Based on cell size and haemoglobin content

19
Q

What is the patholophysiological classification of anaemia and its causes ?

A

Decreased production (low reticulocyte count)‏:

Hypoproliferative (underproduction) – reduced amount of erythropoiesis

Maturation abnormality – erythropoiesis present but ineffective due to:

  1. Cytoplasmic defects: impaired haemoglobinisation (haemolglobin production)
  2. Nuclear defects: impaired cell division

Increased loss or destruction of red cells (high reticulocyte count)‏ due to:

  • Bleeding
  • Haemolysis
20
Q

What is measuring mean cell volume useful for distinguishing between and normocytic anaemia ?

A
  • Microcytic (low MCV)
  • Macrocytic anaemias (high MCV)
  • Normocytic anaemia (normal MCV)
21
Q

What are the normal ranges for MCV including the high and low ranges?

A
  • Microcytic anaemia (MCV <80fl)
  • Normocytic anaemia (MCV 80-100fl)
  • Macrocytic anaemia (MCV >100fl)
22
Q

Recall where haemoglobin is synthesised and what is required to make it and what will shortages in any of these components result in ?

A

Hb synthesised in the cytoplasm

  1. Need Fe2+ & porphyrin ring to form haem group
  2. The haem group the combines with globin to form Hb

Shortage in these results in small red cells with a low hb content (hypochromic i.e. lacking colour because Hb provides the colour to a RBC)

23
Q

What are hypochromic microcytic anaemia due to?

A

Deficient haemoglobin synthesis: cytoplasmic defect

24
Q

What are the causes of hypochromic microcytic anaemias? (remember think about about the componets needed to make Hb)

A

Haem (group) deficiency:

Lack of iron for erythropoiesis (iron deficiency):

  • Iron deficiency (low body iron)‏ - by far the most common
  • Some cases of anaemia of Chronic Disease (normal body iron but lack of available iron) - most normocytic‏

Problems with porphyrin synthesis [ALL VERY VERY VERY RARE]:

  • Lead poisoning – e.g. from painting houses, cooker wear, herbal remedies
  • Pyridoxine responsive anaemias

[Congenital Sideroblastic Anaemia – results in molecular defect in porphyrin ring (v.rare)]

Globin deficiency:

  • Thalassaemia (trait, intermedia, major) (covered in another lecture)
25
Q

Sideroblastic anaemia is another cause of hypochromic microcytic anaemia, when should this be considered ?

A

When microcytic anaemia isnt responding to iron therapy

26
Q

What are the key points to know about siderblastic anaemia ?

A
  • It is a hypochromic microcytic anaemia
  • Diagnosis made on bone marrow Presence of ring sideroblasts in the bone marrow
  • Dysfunctional heme synthesis or processing. This leads to granular deposition of iron in the mitochondria that form a ring around the nucleus of the developing red blood cell. (sideroblast)

Lab findings:

  • Serum Iron: High
  • Increased ferritin levels
  • Normal total iron-binding capacity
  • High transferrin saturation
  • Hematocrit of about 20-30%
  • The mean corpuscular volume or MCV is usually normal or low

Haematology week 1 (16 decks)

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