Gastro - week 4 Flashcards
what is anaemia
when the serum haemoglobin is 2 standard deviations below normal
what is iron deficiency
when the total body iron is low due to absorption not matching demand
what is the epidemiology of iron deficiency anaemia
Iron deficiency anaemia affects 2-5% of males and non-menstruating females
Of these 10% have an underlying GI malignancy
If iron deficient but not anaemic, 1% will have underlying malignancy
what are some causes for IDA
- Poor intake of dietary iron
- Poor absorption e.g. coeliac or post-surgery
- Increased iron (blood) loss e.g. menstruation or cancer
- Increased demand e.g. pregnancy, adolescence
what are the symptoms of IDA
• Often none
• Tiredness, dyspnoea, headache
• Common signs
o Pallor, atrophic glossitis
• Rarer signs
o Koilonychia, leuconycia, tachycardia, angular
cheilosiswhat are the two types of iron
Ferrous iron – Fe2+ is found in red meat and seafood and is readily absorbed by the body – how the body wants it
Ferric iron – Fe3+ - less absorbable – needs to be changed to ferrous iron
what are iron absorption enhancers
- Vitamin C
- Fructose
- Sorbitol
- Alcohol
what are iron absorption inhibitors
- Tannins (tea)
- Calcium, manganese, copper
- Egg and pulse proteins
describe ferritin
Iron stored in the body as ferritin - can be raised if the body is inflamed
If ferritin is normal there is no good way of testing iron deficiency
describe chronic disease anaemia
On a haematological test, iron deficiency anaemia and anaemia of chronic disease look the same.
Chronic disease could be anything like cancer
Inhibits release of iron from the reticular endothelial system
Also reduces erythropoietin release
how can you tell if someone has IDA and not CDA
Ferritin levels and bone marrow iron stores can be used to check for iron deficiency anaemia (would both be low) - transferrin will also be high to move what little iron there is around
Iron deficiency anaemia defined as low haemoglobin in the presence of
• Low ferritin
• Low serum iron in the presence of transferrin >3.0
what is the treatment for IDA
- Optimise diet
- Supplement with iron tablets for 3 months after iron deficiency is 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 can be considered – can be dangerous as body absorbs all of this and only as much oral iron as it needs
describe dysplasia
Dysplasia – disordered growth, architecture and maturation in a tissue, seen down a microscope - an appearance rather than a process
Dysplastic tissue may be neoplastic, show pre-neoplastic changes or revert back to normal
In epithelial tissue, severe dysplasia can be referred to as carcinoma in situ (intraepithelial neoplasm) – not yet able to invade into surrounding tissue
Features
• Hyperchromatism
o Dark staining of nuclei reflecting an increase in DNA content
• Nuclear pleomorphism
o Variation in nuclear shape (and size)
• Loss of orientation
o Many normal epithelial cells show polarity
• Cell crowding and stratification
o Reflects a loss of normal contact inhibition
• Increased and/or abnormal mitotic figures
o Reflects increased cell proliferation
what are soft tissue or connective tissue malignancies called?
called sarcomas
what is intussesception
where a polyp on the bowel is dragged by waves of peristalsis causing the bowel to “telescope”. This causes obstruction of the lumen and compresses the venous drainage, leading to ischaemia
what are the two types of borderline tumours
- Tumours that show extensive local invasion but almost never metastasise. Prone to local recurrence if incompletely excised
- Tumours that appear benign but which can develop distant metastases
what are symptoms of GI neoplasia
- Weight loss
- Tiredness (anaemia)
- Anorexia and vomiting
- Pain caused by obstruction
- Dysphagia
- Alteration in bowel habit
what types of oesophageal cancer are most common where?
Squamous cell carcinoma of the oesophagus most common in the world but the most common oesophageal cancer in the UK in adenocarcinoma – most associated with barrett’s oesophagus
describe gastric carcinoma
• More males than females
• Often presents late
• Familial link around 10%
• Aetiology multifactorial – but mostly things that cause chronic gastritis
• 2 types histologically
o Intestinal
Increased risk in patients with FAP
o Diffuse
Relatively more common in low incidence
areas
Often younger patients
Female>male
Inactivation of CDH1 gene which codes
for E-cadherin, a cell adhesion molecule
describe small intestine cancer
- Uncommon
- Adenocarcinoma
• Neuroendocrine tumours
o Epithelial tumours associated with the synthesis of
hormone or neurotransmitter-like substances
o Range from well differentiated benign to
aggressive poorly differentiated tumours
• Gastrointestinal stromal tumours
o Soft tissue tumour (sarcoma) that can arise anywhere in the GI tract – most commonly stomach
o Related to pacemaker cells in muscularis propria
o Many have activating mutations in the receptor
tyrosine kinase
• Lymphoma (in coeliac disease)
where do colon cancers tend to metastasise?
to the liver
describe colorectal polyps
• Inflammatory – IBD, lymphoid
• Hamartomatous
o Juvenile polyps and polyposis
o Peutz jegher syndrome – pigmentation of lips
- Hyperplastic
- Lesions in the submucosa
• Neoplastic
o Adenomas
Tubular
Tubulovillous
Villous (the more villous the more likely it
is high grade or invasive)
describe colorectal adenoma inc. risk factors and genetics
- Older age cancer
- No gender diff other than rectal which is more common in men
- Most sporadic (not genetic)
• Dietary risk factors
o Excess calories
o Low fibre
o High intake of refined carbs
o High intake of red meat
o Low intake of vitamins
• Other risk factors
o Family history
o Inherited syndromes
o Alcohol
o Smoking
o IBD
o Occupational factors
o Radiation
o Schistosomiasis
• Genetics
o APC/ beta catenin pathway
Inactivation of APC gene (tumour
suppressor) – seen in about 80%
Genetic basis of the inherited FAP
o Microsatellite instability pathway
10-15% of sporadic colorectal carcinomas
(more right sided than left)
Inactivation of DNA mismatch genes
One of these involved in lynch syndrome
Loss of one of these genes increases
mutation rate by up to 1000 fold
Not associated with typical adenoma-
adenocarcinoma sequence
o Serrated neoplasia pathway
More recently identified
Associated with distinctive precursor
lesions showing similarities to
hyperplastic polyps
More common in right bowel
More rapid progression to malignancy
where is alcohol metabolised?
about 10% in stomach and rest in liver
