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Haematology Week 1 2018/19 > 4: Macrocytosis and macrocytic anaemia > Flashcards

4: Macrocytosis and macrocytic anaemia Flashcards

1
Q

What is macrocytic anaemia?

A

Reduction in red blood cell number in which the red blood cells are larger than normal

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2
Q

In macrocytic anaemia, haemoglobin is (high / low) and MCV is (high / low).

A

Hb low

MCV high (> 100 fL)

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3
Q

What is macrocytosis?

A

Increase in red blood cell size

NOT the same as macrocytic anaemia (Hb and red cell count normal)

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4
Q

Normal ranges for MCV vary from hospital to hospital.

On a blood film, what can red blood cells be compared with to say whether or not they are macrocytic?

A

Nucleus of a lymphocyte

because they tend to be larger than an RBC should be

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5
Q

What values of MCV are

a) normal
b) indicative of macrocytosis?

A

a) 80 - 100 fL

b) > 100 fL

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6
Q

Where are red blood cell precursors found?

A

Bone marrow

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7
Q

Before reticulocytes, what are precursor red blood cells called?

Do they have a nucleus?

A

Erythroblast

Yes

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8
Q

What do precursors to red blood cells accumulate as they divide?

A

Hb

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9
Q

Red blood cell precursors get (bigger / smaller) as they divide.

A

smaller

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10
Q

Where are reticulocytes found?

A

Circulation

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11
Q

What do reticulocytes lose before becoming mature RBCs?

A

RNA

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12
Q

What is a megaloblast?

A

Big erythroblast (precursor RBC) with abnormal nucleus

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13
Q

What happens to

a) Hb synthesis
b) DNA synthesis and nuclear maturation
c) RNA synthesis

in a megaloblast?

A

a) Normal

b) Abnormal

c) Normal

i.e this is a problem with the DNA / nucleus, which remember causes a macrocytic anaemia

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14
Q

What does a megaloblast turn into when it differentiates?

A

Macrocyte

Due to nuclear problem, most of the cells have undergone apoptosis, so cell count is reduced (macrocytic anaemia)

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15
Q

What is the main causes of megaloblastic (a type of macrocytic) anaemia?

A

Vit B12 / Folic acid deficiency

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16
Q

Why do Vit B12 and folic acid deficiencies cause megaloblastic anaemia?

A

Both involved in DNA synthesis and nuclear maturation

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17
Q

What genetic process are Vit B12 and folic acid involved in?

A

Gene silencing

18
Q

Which vitamin is carried to the distal ileum by intrinsic factor?

A

Vit B12

19
Q

Which protein carries Vitamin B12 to the duodenum before it is bound to intrinsic factor?

A

R protein

20
Q

In which foods is Vitamin B12 found?

A

Animal products

Red & white meat, fish, eggs, cow’s milk

21
Q

Who is prone to Vitamin B12 deficiency?

A

People who don’t eat animal products

People on PPIs (inadequate stomach acid to liberate Vit B12 from food)

People at risk of malabsorption (overgrowth, surgical resection)

Alcoholics (indaequate nutrition)

22
Q

Which stomach cells produce intrinsic factor?

A

Parietal cells

23
Q

In which autoimmune disease are gastric parietal cells destroyed?

A

Pernicious anaemia

Causes Vit B12 deficiency

24
Q

Who is prone to folate deficiency?

A

Alcoholics (inadequate nutrition)

25
Q

What are the general symptoms of anaemia?

A

Pallor

Fatigue

Difficulty concentrating

Dizziness

Shortness of breath

26
Q

What are specific symptoms of Vit B12 / folic acid deficiency?

A

GI problems - weight loss, diarrhoea, jaundice etc. - suggest a primary GI cause

Glossitis (sore tongue)

Delayed development

27
Q

What irreversible neurological changes are caused by Vit B12 deficiency?

A

Delayed degeneration of dorsal columns (spinothalamic tract)

Dementia

NOT the same as the B1 encephalopathy

28
Q

What are blood film findings specific to macrocytic anaemia caused by Vit B12 / folate deficiency?

A

Macrovalocytes

Hypersegmented neutrophils

29
Q

How is megaloblastic anaemia treated?

A

Treat underlying cause e.g diet, malabsorption

Vit B12 injections in pernicious anaemia

Folic acid supplements

30
Q

What are some causes of isolated macrocytosis?

A

Alcohol

Liver disease

Hypothyroidism

31
Q

What bone marrow response to blood loss can cause a false macrocytosis?

A

Reticulocytosis

because reticulocytosis are immature RBCs and naturally bigger

32
Q

What are cold agglutinins?

What false reading do they cause?

A

Proteins which stick RBCs together in clumps

False macrocytosis

33
Q

Why do patients with pernicious anaemia appear jaundiced?

A

Vit B12 / Folate deficient

MCV increases (macrocytosis)

RBCs can’t pass into the circulation and die in the bone marrow (ineffective erythropoiesis)

Hb broken down into bilirubin > jaundice

34
Q

What does MCV mean?

What unit is it measured in?

A

Mean cell volume

Femtolitres

35
Q

What is the normal range of MCV in femtolitres?

A

80 - 100 fL

ranges vary slightly

36
Q

Which value and above of MCV is abnormal?

A

> 100 fL ish

compare the red blood cell size to the nucleus of a lymphocyte - bigger is abnormal

37
Q

From which dietary sources is

a) vitamin B12
b) folate

obtained?

A

a) Animal products

b) Leafy veg, liver, fortified cereals

38
Q

How long do folate stores last?

A

4 months

39
Q

How long do vitamin B12 stores last?

A

2 - 4 years

40
Q

What is a hypersegmented neutrophil?

A

Neutrophil with nucleus containing 6+ lobes

Haematology Week 1 2018/19 (9 decks)

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