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)
What is capsule endoscopy?
- Minimal and few patients
- Small bowel in middle
- Camera on pill
- Photos
- Downloaded bluetooth
- Angio dysplasia= target
What is the investigative strategy?
- Once both colon and upper GI tract have been assessed then no further GI investigations required for the majority
- No formal diagnosis is common
- Ensure not losing blood from renal tract
- Investigate small bowel if recurrent IDA.
What is the treatment for IDA?
- Optimise diet
- Oral iron supplementation for 3 months after iron deficiency corrected
- Main side effects are constipation, GI upset and dark stools
- If unable to tolerate then some evidence to suggest once daily dosing/alternate day dosing is effective
- If unable to tolerate that then IV iron now safe and quick.
