Microcytic anaemia Flashcards
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
What are the 3 main “building blocks” of haemoglobin?
- Ferrous iron
- Porphyrin
- Globin
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
What is meant by hypochromia?
Lack of colour in red blood cells
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
Which Hb “building block” is affected by thalassaemia?
Globin
Which Hb “building block” is affected by anaemia of chronic disease?
Iron
Which Hb “building block” is affected by iron deficiency?
Iron
Which Hb “building block” is affected by lead poisoning?
Porphyrin
Which Hb “building block” is affected by sideroblastic anaemia?
Porphyrin
What is iron deficiency anaemia?
This is a condition in which low body iron levels results in reduced erythrocyte MCV and decreased haemoglobin levels
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
What are some epithelial changes that can occur in long-term, unmanaged iron deficiency anaemia?
- Skin pallor
- Koilonychia
- Angular cheilitis
What are the main causes of iron deficiency anaemia?
Dietary insufficiency (Absolute or relative)
Blood loss
Malabsorption
Malignancy
What is meant by absolute dietary iron deficiency?
Lack of dietary iron in food
What foods are good sources of iron?
Red meats
Leafy greens
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?
- A small amount of iron can be stored in ferritin in macrophages while the rest is transported away via transferrin
- Chronic inflammation can lead to increased ferritin synthesis within the macrophages by inflammatory cytokines
- This means that more iron is stored in the macrophages and less is transported away
- Inflammatory cytokines also increase plasma hepcidin, which blocks ferroportin-mediated release of iron and further decreases iron release
- Cytokines can also inhibit release of erythropoietin from the kidneys and erythroid proliferation at the bone marrow, while also increasing red blood cell breakdown
- 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)
