Anaemia Flashcards by Katie Clark

What is anaemia?

“without blood”

Reduced red blood cells

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State the parameters for defining anaemia in an adult male (Hb and haematocrit levels)

Hb less than 130g/L

Hct 0.38-0.52

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State the parameters for defining anaemia in an adult female (Hb and haematocrit levels)

Hb less than 120g/L

Hct 0.37-0.47

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What is haematocrit?

Ratio/percentage of whole blood that is made up of red cells if the sample was left to settle

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What cells represent circulatory red cells that have just left the bone marrow?

Reticulocytes

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How does the blood film of reticulocytes appear?

Polychromatic

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How is anaemia classified by pathophysiology?

Decreased production of red cells (reduced or ineffective erythropoiesis) [low reticulocyte count]
Increased destruction of red cells (haemolysis, bleeding) [high reticulocyte count)

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What morphological characteristic can be used to classify anaemia?

Mean cell volume

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How can mean cell volume be used to distinguish between cytoplasmic and nuclear defects in erythropoiesis?

Low MCV suggests problems with haemoglobinisation in the cytoplasm
High MCV suggests problems with red cell maturation

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Deficiency in haemoglobin production results in what type of anaemia?

Microcytic anaemia - cells are small (low MCV) and hypochromic (lack colour)

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List some causes of microcytic anaemia

Haem deficiency (lack of iron, problem with porphyrin synthesis)
Globin deficiency (thalassaemia)

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Circulating iron is bound to what?

Transferrin

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Iron is stored as ferritin where in the body?

Liver

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How can iron deficiency be confirmed?

Anaemia (less functional iron)
Low ferritin (less stored iron)

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List some causes of iron deficiency

Dietary insufficiency
Blood loss
Malabsorption
Pregnancy

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High mean cell volume is associated with which type of anaemia?

Macrocytic anaemia - cells are big

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What is the difference between macrocytosis and macrocytic anaemia?

Macrocytosis: raised MCV, normal RBC count

Macrocytic anaemia: raised MCV, low RBC count

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How many binding sites are there on a transferrin molecule?

What unit is MCV measured in?

Femtolitres (fl)

1 femtolitre = 10^-15 litres

What is the range for a normal MCV?

80-100 fl

What is a megaloblast?

Abnormally large red cell precursor with an immature nucleus

Macrocytic anaemia can be caused by megaloblastic cells. What is the characteristic microscopic appearance of these red cells?

Immature nucleus
Normal cytoplasm
Big cell

What is the consequence of a megaloblastic cell?

Cytoplasm and haem synthesis is fully developed even though nucleus is immature; cell senses it has enough Hb and doesn’t divide anymore, leading to macrocytosis

List some causes of megaloblastic anaemia

B12 deficiency
Folate deficiency
Drugs
Inherited conditions

Why does lack of B12 and folate cause megaloblastic anaemia?

B12 and folate are essential cofactors for nuclear maturation - enable reactions for DNA synthesis Thus deficiency leads to DNA defects

Which 2 biochemical cycles involving folate and B12 are involved in DNA synthesis?

Methionine cycle | Folate cycle

Where in the body does B12 bind to intrinsic factor?

Ileum

List some causes of B12 deficiency

``` Dietary insufficiency (vegetarians) Small bowel resection Atrophic gastritis Gastrectomy Pancreatitis Malabsorption (Coeliac, IBD) ```

Where in the body is dietary folate absorbed?

Duodenum and jejunum

How long does the body store B12 and folate respectively?

B12: 2-4 years Folate: 4 months

State the daily requirements of B12 and folate

B12: 1-3 micrograms/day Folate: 100 micrograms/day

List some causes of folate deficiency

Dietary insufficiency Malabsorption Excess utilisation (haemolysis, pregnancy, malignancy) Drugs (anticonvulsants)

List clinical features of B12 and folate deficiency

``` Signs of anaemia Weight loss Diarrhoea Infertility Sore tongue Jaundice Developmental problems ```

B12 deficiency can cause issues with the myelin sheath. What neurological problems may result?

``` Dorsal column abnormality Lateral tract degeneration Neuropathy Dementia Psychiatric manifestations ```

What is pernicious anaemia?

Autoimmune condition where gastric parietal cells are destroyed, causing decreased intrinsic factor and thus B12 deficiency

How is macrocytic anaemia diagnosed in the lab?

Blood film: macrovalocytes and hypersegmented neutrophils (more than 5 segments) B12 and folate serum assay Antibodies: parietal-cell, intrinsic factor

List treatment for megaloblastic anaemia

Treat cause B12 injections Folic acid tablets Red cell transfusion if life-threatening

List some causes of non-megaloblastic anaemia

Alcoholism Liver disease Hypothyroidism Marrow failure

What is spurious macrocytosis?

The size of the red cell is normal but the MCV is high

What causes a spurious macrocytosis?

Acute blood loss/red cell breakdown response: increase in reticulocytes, which are bigger than red cells, which are analysed as part of MCV

Reticulocytosis is a marker of what?

Red cell production

What compound is a product of red cell breakdown that causes pale urine?

Urobilinogen

What is the commonest cause of hypochromic microcytic anaemia?

Iron deficiency