Week 3 Flashcards
What part of the intestine can an endoscopy not visualise well?
Ileum
What is fluoroscopy useful for visualising?
Perforation in upper GI tract
What can fluoroscopy be used to test for?
Blockages in swallowing
What radiological scan is used to image the colon?
CT
What structures is ultrasound useful for imaging?
Liver, pancreas and gall bladder
What is the best test to detect gall stones?
Ultrasound
Describe some disadvantages of MRI in GI radiology
Very slow, and small space can make claustrophobic patients uncomfortable. Also cannot be used on patients with pacemakers.
What are the main uses of CT in GI radiology?
Diagnose disease, staging of malignancy, assess response to treatment and percutaneous biopsy
What is PET-CT?
Functional imaging of metabolic activity fused with anatomical information from CT
What is PET-CT useful for?
Staging, and finding the extent of cancer
What are the roles of MRI in GI imaging?
Non-invasive imaging of biliary tree and small bowel, local staging of rectal cancer and diagnosing liver lesions
What are right upper quadrant pain, jaundice and pale stools indicative of?
Gall stones
What imaging modality could be used in the investigation of appendicitis?
Ultrasound (maybe CT)
What does pneumoperitoneum indicate?
Perforation, usually from a gastric or duodenal ulcer
What can CT angiography be used for in patients with gastric/duodenal ulcers?
Identification and treatment of acute bleeding
How can CT angiography be used to treat acute bleeding from a perforated gastric or duodenal ulcer?
Coli embolisation:
- intimal damage leads to thrombogenic factors
- fibres provide thrombogenic surface
- continue to inject dye until no leakage out of blood vessel
- mechanical occlusion
What is always assumed to be a sign of colon cancer in men and post-menopausal women?
Microcytic anaemia
What is the total body iron content?
4 grams
What is iron stored as in cells?
Ferritin and haemosiderin
How is iron transported in plasma, and what is the transporters iron saturation?
Transferrin (a glycoprotein synthesised in hepatocytes). 30% saturated with iron
How much iron is absorbed from an average western diet?
15 mg
Where does iron absorption take place?
Predominantly in the duodenum (duodenal enterocytes)
Is haem iron or non-haem more readily absorbed?
Haem iron (non-haem released from foodstuffs by acid digestion proteolytic enzymes in stomach)
How is Fe2+ taken into the enterocyte?
By the divalent metal transport 1 (DMT1), an electrogenic pump
What is ferroportin?
A transmembrane protein, essential in the export of iron from the enterocyte
What hormone interacts with ferroportin to regulate GI iron absorption, and RES iron release?
Hepcidin
How much iron does the RES store?
500 mg
After being released by the RES, what cells take up iron from the plasma?
Erythroblasts and hepatocytes, via the Tf receptors
Where is transferrin synthesised?
The liver
How many iron atoms can each transferrin bind?
2
Does the bulk of iron in plasma come from the diet or from stored iron in the RES?
The RES
How is iron delivered to tissues?
Iron is delivered to tissues by binding of the transferrin-iron complex to transferrin receptors found on the cell surface
Where is the highest concentration of transferrin receptors found?
On RBC precursors (approx 80%)
What is hereditary haemochromatosis?
An autosomal recessive disorder of iron metabolism, causing iron overload
Abnormalities with which gene are responsible for the majority if HH cases?
HFE gene, which is essential in hepcidin synthesis
What is the role of hepcidin?
Hepcidin reduces the levels of iron in plasma
What are some symptoms/complications of HH?
Bronze pigmentation in the skin, diabetes, restrictive cardiomyopathy and cirrhosis
How is HH treated?
Weekly venesection to remove excess iron by removing 500 mls of blood
What period of time does the hepatitis virus have to be present for to become chronic hepatitis?
6 months
How are hepatitis A and E transmitted?
Faeco-oral, contaminated food and water, person-person
What is the main determinant of severity of hepatitis A infection?
Age, mostly asymptomatic in children under 5 years old
Are there any treatments for hepatitis A?
No (prophylaxis is available with vaccine)
Who is offered the hepatitis A vaccine?
People travelling to at risk areas, homosexual men, intravenous drug users and chronic liver disease patients
How many genotypes of hepatitis E are there?
4