Microcytic anaemia Flashcards by Jack Molyneux

What is microcytic anaemia?

Microcytic anaemia is a condition in which there is a reduced mass of red blood cells, with present red blood cells having a reduced MCV

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What are the 3 main “building blocks” of haemoglobin?

Ferrous iron
Porphyrin
Globin

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How does microcytic anaemia occur?

Hb is synthesised in the cytoplasm of precursor cells
Division of these cells is only limited by an excess of Hb
If there is a decreased level of Hb synthesis, then the cells will still divide, but will contain less Hb, so will be smaller

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What is meant by hypochromia?

Lack of colour in red blood cells

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What are the 5 main causes of microcytic anaemia?

TAILS:
T = Thalassaemia
A = Anaemia of chronic disease
I = Iron deficiency (Most common)
L = Lead poisoning
S = Sideroblastic anaemia

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Which Hb “building block” is affected by thalassaemia?

Globin

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Which Hb “building block” is affected by anaemia of chronic disease?

Iron

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Which Hb “building block” is affected by iron deficiency?

Iron

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Which Hb “building block” is affected by lead poisoning?

Porphyrin

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Which Hb “building block” is affected by sideroblastic anaemia?

Porphyrin

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What is iron deficiency anaemia?

This is a condition in which low body iron levels results in reduced erythrocyte MCV and decreased haemoglobin levels

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Describe the pathophysiology of iron deficiency anaemia?

As iron levels begin to drop, ferritin stores are released

Once these stores are exhausted, iron deficiency erythropoiesis occurs and MCV begins to fall, causing development of anaemia

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What are some epithelial changes that can occur in long-term, unmanaged iron deficiency anaemia?

Skin pallor
Koilonychia
Angular cheilitis

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What are the main causes of iron deficiency anaemia?

Dietary insufficiency (Absolute or relative)
Blood loss
Malabsorption
Malignancy

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What is meant by absolute dietary iron deficiency?

Lack of dietary iron in food

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What foods are good sources of iron?

Red meats
Leafy greens

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What types of diet can lead to iron deficiency?

Vegetarian
Vegan

Why is dietary iron deficiency unlikely in men?

There is no menstrual blood loss, so there is unlikely to be such a severe iron deficiency in just dietary insufficiency

What is meant by relative dietary insufficiency?

This is when there is a normal amount of iron intake, but something is increasing the levels of bodily iron usage

What are some causes of blood loss leading to iron deficiency anaemia?

Trauma
GI bleeding
Menorrhagia

What is the normal monthly blood loss through menstrual bleeding?

30-40ml (15-20mg per month)

What monthly blood loss is classified as menorrhagia?

> 60ml blood loss (>30mg iron loss)

What are some causes of iron malabsorption?

Coeliac’s disease
Achlorhydria

Where in the gut is iron absorbed?

Duodenum and jejunum

What are some long term, specific signs and symptoms of iron deficiency anaemia?

- Koilonychia (Spooning of the nails) - Angular cheilitis - Atrophic glossitis (Atrophy of tongue papillae leads to smoothening) - Brittle hair and nails

How is iron deficiency anaemia diagnosed?

Iron deficiency anaemia is diagnosed using haemoglobin concentration, serum ferritin and % saturation of transferrin

What conditions can lead to a low % saturation of transferrin?

Iron deficiency anaemia Chronic disease Genetic haemochromatosis

What investigations may be required in iron deficiency anaemia to rule out GI blood loss?

QFIT Colonoscopy

How is iron deficiency anaemia managed?

Supplementary iron (IV or oral) 100-200mg per day 30 minutes before a meal

How quickly should healthy bone marrow increase Hb concentration by in iron supplementation?

7-10g/L/week

What foods should patients avoid eating with iron tablets?

- Milk - Calcium - Antacids - High fibre foods - Caffeine

What are some common side effects of supplemental iron tablets?

- Constipation - Nausea - Vomiting - Abdominal pains - Dark stools

When should bloods be taken again after initial treatment?

2 weeks

Describe the pathophysiology of anaemia of chronic disease?

1. A small amount of iron can be stored in ferritin in macrophages while the rest is transported away via transferrin 2. Chronic inflammation can lead to increased ferritin synthesis within the macrophages by inflammatory cytokines 3. This means that more iron is stored in the macrophages and less is transported away 4. Inflammatory cytokines also increase plasma hepcidin, which blocks ferroportin-mediated release of iron and further decreases iron release 5. Cytokines can also inhibit release of erythropoietin from the kidneys and erythroid proliferation at the bone marrow, while also increasing red blood cell breakdown 6. This, therefore decreases iron supply to the marrow, causing microcytic, hypochromic anaemia

What is the usual benefit of macrocytic iron retention in inflammation?

It is a protective mechanism to reduce the supply of iron to pathogens

What is the most common disease that can cause anaemia of chronic disease?

Chronic kidney disease, due to chronic inflammation and pathological decrease in EPO production

How will anaemia of chronic disease, caused by chronic kidney disease present?

Oedema Hypertension Excoriation of the skin

What is sideroblastic anaemia?

This is an excess iron build up in the mitochondria due to failure to incorporate iron into haemW

What are some causes of sideroblastic anaemia?

Inherited MDS Lead poisoning Alcohol excess

What disease is shown in this blood film?

Sideroblastic anaemia (Blue granules show iron build up in mitochondria)