Intro to anaemia and microcytic anaemia Flashcards

1
Q

What is the definition of anaemia?

A

Reduced total red cell mass; use Hb concentration as a surrogate marker
Can also use haematocrti

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2
Q

What are the cut offs for anaemia?

A

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

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

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3
Q

How is Hb conc measured using a spectrophotometric method?

A

Lyse red cells to create Hb solution
Stabilise Hb molecules
Measure optical density at 540 nm
Hb conc calculated against known reference standard conc solution

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4
Q

What is beer’s law?

A

Optical density is proportional to the concentration of Hb

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5
Q

What is Hb/hct not a good marker of anaemia?

A

Rapid exsanguination

Haemodilution

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6
Q

What is the normal response to anaemia?

A

Increased red cell production - reticulocytosis

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7
Q

What are reticulocytes?

A

Red cells that have just left the bone marrow
Larger than average red cells
Still have RNA
Stain purple/ deeper red as a consequence
Blood film appears polychromatic

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8
Q

Why does polychromasia result in reticulocytes?

A

Residual RNa in the cell gives the classic blue-grey appearance

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9
Q

How is haematocrit calculated?

A

Red cell number x red cell size

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10
Q

What is the purpose of the blood film?

A

Cellular morphology

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11
Q

What does the reticulocyte count assess?

A

Marrow response

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12
Q

How can anaemia be classified on pathophysiological terms?

A

Decreased production (low retic count)
Increased loss or destruction of red cells (high retic count). Bleeding or haemolysis
Redistribution - (splenomegaly)
Decreased production (low retic count) :
Hypoproliferative - reduced amount of erythropoiesis
Maturation abnormality - erythropoiesis present but ineffective (cytoplasmic defects - impaired hemoglobinization. Nuclear defects - impaired cell division)

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13
Q

How can MCV determine the type of anaemia?

A

Low (microcytic) = issue with haemoglobinisation

High (macrocytic) = nuclear maturation

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14
Q

Where does haemoglobin synthesis occur in the cell?

A

Cytoplasm

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15
Q

Where is haem synthesized in the cell?

A

Mitochondrion

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16
Q

What makes up haem?

A

Porphyrin ring

Iron (Fe 2+)

17
Q

What does iron deficiency anaemia present like?

A

Microcytic hypochromic anaemia: deficient haemoglobin synthesis (cytoplasmic defect)

18
Q

What are the causes of hypochromic microcytic anaemia?

A
Haem deficiency: 
Iron deficiency 
Porphyrin synthesis (lead poisoning) 
Congenital sideroblastic anaemia 
Globin synthesis deficiency - thalassaemia (trait, intermedia, major)
19
Q

What is the function of iron?

A
Oxygen transport (Hb, myoglobin) 
Electron transport (mitochondrial production of ATP)
20
Q

In a normal patient (not on supplements), how much iron is absorbed per day?

A

1mg/ day

21
Q

How much iron is stored in red cell Hb?

A

2500 mg

22
Q

How is iron transported around the body?

A

Transferrin

23
Q

How is iron stored in the liver and macrophages?

A

Ferritin

24
Q

How much iron can bind to transferrin?

A

2 binding sites

25
Q

What does the % saturation of transferrin measure?

A

Iron supply; low in iron deficiency anaemia and anaemia of chronic disease
Increased in genetic haemochromatosis

26
Q

How much iron can a ferritin protein stor?

A

4000 ferric ions

27
Q

What is serum ferritin an indirect measure of?

A

Storage iron

28
Q

How can iron deficiency be confirmed?

A

Anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)

29
Q

What can cause a relative iron deficiency?

A

Women of child bearing age
Developing foetus
Pregnant women

30
Q

What can cause an absolute iron deficiency?

A

Veggie/ vegan diets
Blood loss
Menorrhagia
Coeliac disease, achlorhydria

31
Q

What can cause chronic blood loss?

A

Menorrhagia
GI; tumour, ulcer, NSAIDs
Haematuria

32
Q

What is defined as heavy menstrual blood loss?

A

> 60ml i.e. >30mg iron/month

33
Q

What are the sequential consequences of a negative iron balance?

A

Exhaustion of iron stores
Iron deficient erythropoiesis; falling red cell MCV
Microcytic anaemia
Epithelial changes; dry skin, koilonychia

34
Q

Is iron deficiency anaemia a diagnosis?

A

No; a symptom. Need to determine why there is iron deficiency