Haematology Flashcards
What are the 4 mechanisms behind iron deficiency anaemia?
- Increased loss of iron
- Malabsorption
- Reduced intake
- Increased utilisation of iron
What Hb levels indicate iron deficiency anaemia in men and non-pregnant women?
Men - <130g/L
Non-pregnant women - <120g/L
What is the most common form of anaemia?
Iron deficiency - globally affects 500 million people
How much iron on average is absorbed daily from the diet?
Only 1mg on average of iron is absorbed daily from the diet so even modest blood loss over time can lead to iron deficiency
Give some conditions that can cause iron deficiency anaemia via an increased loss of iron?
- Menorrhagia
- GI bleeding e.g. ulcers
- Hookworm
- IBD
- Malignancy
What is the biggest risk factor for iron deficiency anaemia due to reduced intake of iron>
Poor diet – Main sources of dietary iron; meat, leafy green vegetables, fortified foods including bread and cereals
Vegans, vegetarians, poor or restricted diets at risk
Where does most iron absorption occur?
Small intestine
Which conditions can result in iron deficiency anaemia due to malabsorption?
- Coeliac disease & IBD – result in reduction in the mucosal surface area available for iron absorption
- Gastrectomy & cystic fibrosis – malabsorption of iron occurs at pre-mucosal level when digestive enzyme activity is disrupted
- Intestinal resection & jejuno-illeal bypass: inadequate absorption in the small intestine
- Lymphoma: causes lymphatic obstruction leads to post-mucosal absorption
- Drugs: Reduce absorption of iron e.g. tetracyclines/quinolones (chelate iron), PPIs (decrease gastric acid necessary for iron absorption)
Why can IBD and coeliac disease predispose to iron deficiency anaemia?
Conditions result in reduction in the mucosal surface area available for iron absorption
Why can CF predispose to iron deficiency anaemia?
malabsorption of iron occurs at pre-mucosal level when digestive enzyme activity is disrupted
Why can PPIs predispose to iron deficiency anaemia?
decrease gastric acid necessary for iron absorption
What 2 patient populations are at risk of iron deficiency anaemia due to increased utilisation of iron?
- Pregnancy
- Growth spurts in children
Describe the MCV in iron deficiency anaemia
Low (microcytic)
Describe the appearance of RBCs in iron deficiency anaemia
Higher % of hypochromic cells (pale cells)
What type of heart failure can iron deficiency anaemia cause?
High-output heart failure
What are 2 other causes of microcytic hypochromic anaemia? (i.e. differentials for iron deficiency anaemia)
- Thalassaemia
- Sideroblastic anaemia
What is thalassaemia?
A genetic defect of Hb production common in certain parts of the world e.g. Mediterranean coast
What is sideroblastic anaemia?
A congenital or acquired inability to integrate iron into haemoglobin
Give some causes of anaemia of chronic disease?
- Inflammatory arthritis
- Cancer
- Kidney disease
- Infections (e.g. TB, HIV)
What symptoms are common in iron deficiency anaemia?
N.B. Iron deficiency anaemia is often asymptomatic or only causes mild symptoms, especially if the anaemia develops gradually in otherwise healthy individuals (able to compensate).
- Lethargy
- Tiredness
- Weakness
- Jaundice
- Heavy periods
- Change in bowel habits
What red flags may be seen in iron deficiency anaemia?
- Dysphagia
- Weight loss
- Dyspepsia
- Abdominal pain
- Rectal bleeding
- Change in bowel habit
Clinical signs potentially seen in iron deficiency anaemia?
- Conjunctival pallor
- Pale mucosal membranes (mouth)
- Angular cheilitis (ulcers/cracking at corners of mouth)
- Atrophic glossitis (painful tongue with loss of papillae)
- Koilonychia (spoon-shaped nails)
- Dry skin and hair
- In severe anaemia:
- Tachycardia
- Murmurs
- Signs of cardiomegaly
- Sins of heart failure e.g. peripheral oedema
results of FBC in iron deficiency anaemia?
- Low Hb - anaemia
- Low MCV (<95fl) - microcytic
- Reduced MCH - hypochromic
- Reduced MCHC
- Increased red cell distribution width (RDW)
What is the MCH?
The mean corpuscular haemoglobin is he average mass of haemoglobin per red blood cell in a sample of blood → diminished in hypochromic anaemias.
What is MCHC?
The mean corpuscular hemoglobin concentration (MCHC) is the average concentration of hemoglobin in your red blood cells.
What does an increased red cell distribution width (RDW) indicate?
indicates variation in size of RBCs
Describe the ferritin levels in iron deficiency anaemia
Low - as iron stores in the body are mobilised to counteract the iron deficiency
Ferritin is an acute phase reactant. What does this mean?
It rises in inflammatory states
Patients who are iron deficient may appear to have normal (or even raised) serum ferritin levels in the context of acute inflammation (infection, autoimmune disease)
Describe the transferrin saturation levels in iron deficiency anaemia
Low - as less iron to saturate the transferrin
Describe the total iron binding capacity (TIBC) in iron deficiency anaemia
Raised total iron-binding capacity (TIBC) → there is increased capacity to bind iron due to reduced levels of iron
In what form is iron best absorbed?
In its ferrous state (Fe2+)
Once absorbed into the bloodstream, what is iron bound by?
Transferrin
What stores iron?
Ferritin
Describe a blood film in iron deficiency anaemia
Hypochromic cells (pale) which differ in size (anisocytosis) and shape (poikilocytosis)
Define anisocytosis
having red blood cells (RBCs) that are unequal in size