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Hematology > Introduction to Anaemia and Microcytic Anaemias > Flashcards

Introduction to Anaemia and Microcytic Anaemias Flashcards

1
Q

Definition of anaemia

A

Reduced total red cell mass

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2
Q

What are the surrogate markers for anaemia?

A

Haemoglobin

Haematocrit

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3
Q

What are the normal Hb ranges?

A

Adult males
Hb <130g/L
Hct 0.38-0.52

Adult females
Hb <120g/L
Hct 0.37-0.47

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4
Q

How is Hb measured by spectophotometry?

A
  1. lyse the red cells to create Hb solution
  2. Stabilise Hb molecules using Cyan-metHb
  3. Measure the optical density (OD) at 540nm
  4. OD Proportional to the concentration (Beer’s Law)
  5. Hb concentration calculated against known reference standard cyan-metHb concentration solution
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5
Q

Name the physiological response to anaemia with a functional bone marrow

A

Reticulocytosis - increased red cell production

This response takes a few days

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6
Q

What are reticulocytes?

A

Immature RBC
Larger than average RBC
Still have RNA remnants

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7
Q

Why does reticulocytes appear purple/deep red on staining?

A

Presence of RNA remnants

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8
Q

Describe the appearance of blood film with reticulocytes

A

Polychromatic

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9
Q

List the measured red cell indices

A

Hb concentration
Number of red cells (conc.)
Size of red cells - MCV

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10
Q

List the calculated indices

A

Haematocrit
Mean cell Hb
Mean cell Hb concentration

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11
Q

What are the pathophysiological classifications of anaemia?

A

a) decreased production (low retic count as not producing red cells)
b) Increased loss or destruction (high retic count as BM normal)

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12
Q

List the types of anaemia due to decreased production

A

a) Hypoproliferative - reduced AMOUNT of erythropoeisis

b) Maturation abnormality - erythropoeisis present but INEFFECTIVE
i. Cytoplasmic defects: impaired haemoglobinisation
ii. Nuclear defect - impaired cell division

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13
Q

List the causes of anaemia due to destruction of red cells

A

bleeding

Haemolysis

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14
Q

How to interpret MCV

A

Low - microcytic - problem with hemoglobinisation

High - macrocytic - problem with maturation

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15
Q

Where in the cell is Hb synthesised?

A

Cytoplasm

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16
Q

What are the morphological features of red cells in anaemia due to deficient Hb synthesis?

A

Microcytic (small)

Hypo-chromic (lacking in colour

17
Q

Shortage of which components leads to microcytic, hypochromic anaemia (low Hb)?

A

Globin

Haem (porphyrin ring, Fe2+)

18
Q

What are the two BROAD causes of hypochromic, microcytic anaemias?

A

Haem deficiency

Globin deficiency

19
Q

List the causes of haem deficiencies

A

Lack of iron for erythropoiesis

Problems with porphyrin synthesis (extremely rare) - lead poisoning, pyridoxine responsive anaemia

Congenital sideroblastic anemia

20
Q

List the causes of globin deficiency

A

Thalassemia

21
Q

Which molecule is circulating iron bound to?

A

Transferrin

22
Q

What is the role of macrophages in iron metabolism

A

Iron is transferred to bone marrow macrophages which feed it to the red cell precursor

23
Q

Where is iron stored in ferritin?

A

liver

24
Q

Which test assesses functional iron?

A

Haemoglobin

25
Q

Which test assesses transported iron?

A

Serum iron
Trasnferrin
Transferrin saturation

26
Q

Which test assesses storage iron?

A

Serum ferritin

27
Q

Describe structure and function of transferrin

A

Protein with two binding sites fro iron atoms

Transfers iron from donor tissues (macrophages, intestinal cells, hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)

28
Q

Which test measures iron supply?

A

% saturation of transferrin with iron

29
Q

In which scenarios will transferrin be increased and reduced?

A

Iron deficiency anemia - reduced

Anemia of chronic disease - reduced

Genetic haemochromatosis - increased

30
Q

What is the significance of ferritin levels?

A

Reflects intracellular ferritin synthesis in response to iron status of the host

INDIRECT measure of storage iron

NOTE: ferritin is also an acute phase reactive protein and thus may not be an accurate representation of iron stores

31
Q

Which parameters confirm iron deficiency?

A

combination of anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)

32
Q

List the causes of iron deficiency

A
  1. Insufficient intake to meet physiologic requirement
    a) relative - children and pregnant women
    b) absolute - vegetarian diet
  2. Malabsorption - chron’s, coeliac, achlorhydria
  3. Blood loss - menorrhagia, GI (tumours, ulcers, NSAIDS), hematuria
33
Q

What are the sequential consequences of negative iron balance?

A
  1. Exhaustion of iron stores
  2. Iron deficient erythropoiesis (falling red cell MCV)
  3. Microcytic anemia
  4. Epithelial changes - skin, koilonychia

Hematology (9 decks)

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