Anaemia Flashcards
What is anaemia?
where serum haemoglobin levels are 2 standard deviations below the normal
What is iron deficiency?
when the total body iron is low as a result of absorption not matching demand.
Describe the epidemiology of iron deficiency
- Iron deficiency anaemia affects 2-5% of adult males and non-menstruating females.
- Of these around 10% will have an underlying GI malignancy
- If iron deficient but not anaemic, around 1% will have an underlying malignancy
What are the causes of iron deficiency?
- Poor intake of dietary iron
- Reduced absorption (malabsorption) e.g coeliac, post surgical
- Increased iron (blood) loss e.g. menstruation, cancer
- Increased demand e.g. pregnancy, adolescence
What are the signs and symptoms of iron deficiency anaemia?
-Often none (asymptomatic)
-Common symptoms: tiredness, dyspnoea, headache
-Common signs: pallor, atrophic glossitis
Rarer signs: koilonychia, leukonychia, tachycardia, angular cheilosis
Foods with iron
- Chickpeas
- Lentils
- Cereals and breads fortified with iron
- Leafs
- Pulses
Describe ferric iron absorption (non-haem Fe3+)
- Food: non-haem iron from plants in the oxidised Fe3+ ferric form is less absorbable compared to haem iron
- Stomach: some Fe3+ reduced to Fe2+ in acid conditions
- Small intestine: some Fe3+ forms insoluble complexes at high pH of small intestine, lowering absorption rates and increasing excretion
Describe ferrous iron absorption (haem Fe2+)
- Food: haem iron from haemoglobin in meat and fish in reduced Fe2+ form, highly absorbable
- Stomach: haem containing iron in Fe3+ form is hydrolysed from protein globin component
- Small intestine: Fe2+ remains soluble as it is bound to proteins and is absorbed through enterocytes
What are iron absorption enhancers in the duodenum?
- Vitamin C
- Fructose
- Sorbitol
- Alcohol
What are iron absorption inhibitors in the duodenum?
- Tannins (tea)
- Oxalates
- Polyphenols
- Phytates
- Egg and pulse proteins
- Calcium
- Copper
- Manganese
What is iron used for in the body?
- Haemoglobin (60%)
- Myoglobin
- Enzymes
- Storage
- Excretion
What is the absorption of iron per day?
- 1mg iron per day (about 10%)
- Haemochromatosis= 2-4 mg per day
What is ferritin?
- Body stores iron in cells as ferritin= marker of total body iron store
- Can be an acute phase reactant in inflammation (so elevated)
- Serum iron is how iron is moved around body
- Free iron is transient= leaves ferritin linked to transporter transferrin
How can anaemia of chronic disease be confused with iron deficiency anaemia?
-In terms of full blood count (size of cells)- small in both
-Amount of blood similar
-
What is the mechanism of Anaemia of Chronic Disease?
-Ongoing inflammatory stimulus
-Affects blood and iron in 4 ways
=Increases hepatic synthesis of hepcidin, inhibits release from iron in endothelial system so held in wrong places
=Augments hemophagocytosis (so less release of recycled iron via ferroportin)
=Inhibits erythroid proliferation (limited availability of iron)
=Inhibits erythropoietin release
How can we tell the difference between IDA and AoCD?
-Ferritin low= IDA
-Serum iron unhelpful
-Transferrin
=IDA= make more so can move what stores it has to where it needs to be
=AoCD normal or low as don’t need to move around
What are the local guidelines for IDA?
Iron deficiency anaemia is defined as a low haemoglobin in the presence of either
=Low ferritin (best diagnostic marker)
=Low serum iron in the presence of transferrin >3.0
What are the local guidelines for IDA in causes?
-Loss of iron (menstrual blood loss, GI blood loss, renal tract blood loss)
-Malabsorption (previous gastric surgery, Coeliac disease)
-Poor dietary iron intake (poor diet, lifestyle choices or cultural beliefs)
-May be contributing factors:
=Menstrual blood loss is the commonest cause overall
=Testing for Coeliac disease (anti tTG antibodies) is worthwhile
Which investigation is appropriate for a young women with IDA with no symptoms?
Coeliac serology
What investigations are appropriate for an elderly woman with asymptomatic IDA?
Post menopausal -Endoscopy and colonoscopy usually As unwell, more difficult =Option if she wants to do nothing =Endoscopy less invasive into stomach as collapsed bag- to exclude cancer and ulcer
Describe a standard endoscopy
-Back of throat around back of pharynx, oesophagus and stomach and duodenum (D2/3)
-Retroflexion to look at stomach
-Numb gag reflex
-Lying down, nurse sucks saliva out
=Topical lidocaine to back of throat, awake and aware
-Topical lidocaine as well as sedation= midazolam, fentanyl
What are the pros and cons of transnasal endoscopy?
Positives: Better tolerated (thinner) -Less gagging and no mouth guard Usually only under local anaesthetic Biopsy standard equivalency Endoscopy is the only test able to adequately visualise the stomach
Negative: unable to perform most therapeutic procedures
= no bleeding
What are the pros and cons of standard colonoscopy?
Laughing gas analgesic, 30-40 min procedure
Positives:
Remains the gold standard
Able to take biopsies and perform polypectomy
Negatives: Invasive Can be uncomfortable Need to take prep Can miss lesions Possibilities of complications: bleeding/perforation -Caecum often missed
What are the pros and cons of CT colonoscopy?
Positives:
Mostly non invasive
Can use min prep for frail patients (faecal tagging to contrast bowel contents and wall)
Fast (10mins vs 30mins)
Less risks
As effective as colonoscopy for polyps>5mm
Negatives:
Still need to take prep (unless min prep)
Radiation dose
If shows lesion will still need colonoscopy
Can result in incidentalomas (find something else that requires follow up)
