Small intestinal disorders and investigation Flashcards
Functions of the small intestine? (4)
Digestion
Absorption
Barrier functions
Endocrine and neuronal control functions - Controlling the flow of material from the stomach to the colon and motility
Why is the breakdown process (digestion) controlled?
to avoid osmotic shifts
Where does the final hydrolysis and absorption occur?
at brush border
Proteins are broken down into what?
oligopeptides and amino acids
Name 2 enzymes involved in digestion process
trypsin
chymotrypsin
How is fat digested?
pancreatic lipase
absorption of glycerol and free fatty acids
via lacteal and lymphatic system
How are carbohydrates digested?
Pancreatic amylase
Breakdown to disaccharides
Final digestion by brush border disaccharidase
What are the barrier functions of the small intestine
Low bacterial population so has a toxic environment - Digestive enzymes - Bile salts - Presence of IgA etc
Maintaining a barrier against pathogens
- Immune sampling
- Monitoring the presence of pathogens
- Translocation of Bacteria
- Gut Associated Lymphoid Tissue (GALT)
Investigations looking at the structure of the small intestine (4)
Small bowel biopsy
- Endoscopy
CT Scan
MRI enterography
Capsule enterography - image using pill camera
Tests for bacterial overgrowth? (2)
H2 Breath test
- Lactulose or glucose substrate
- Very unreliable
Culture a duodenal or jejunal aspirate
Symptoms associated with small bowel diseases (5)
Weight Loss
Increased appetite
Diarrhoea
- Usually watery
- Sometimes steatorrhoea
Bloating
Fatigue
Signs of deficiencies:
Iron
Vitamin A
Vitamin C
Vit B complex
Iron - B12 level, Folate
Vit A - Night blindness
Vit C - scurvy
Vit B complex - thiamine (memory, dementia) or Niacin (dermatitis, unexplained heart failure)
Clubbing can be a sign of what diseases
coeliac disease
Crohn’s
Scleroderma (scarring and thickening of the tissue) can be a sign of which disease
systemic sclerosis
Aphthous ulceration
can be a sign of what diseases
coeliac disease
Crohn’s
What is dermatitis herpetiformis
Cutaneous manifestation of coeliac disease
- Blistering
- Intensely itchy
- Scalp, shoulders, elbows, knees
- IgA deposit in skin
How common is coeliac disease in UK
1: 111 screening
1: 300 clinical diagnosis
Tests for coeliac disease
Serology is approximately
90% specific
90% sensitive
IgA tests more reliable than IgG
But only if you make IgA
A significant number of people don’t
Selective IgA deficiency is relatively common, about 0.1 to 1% of population
But 2 to 3% of coeliacs
Therefore, always check the total plasma IgA as well
What is the gold standard confirmatory test for coeliac disease?
distal duodenal biopsy - may show villous atrophy
Genes that are associated with coeliac disease?
HLA DQ2 or DQ8
30% of the population have this though, not just coeliac’s however 97% of coeliac’s do
What is Gliadin
a fraction of gluten found in Wheat, Rye and Barley
people may be sensitive to gliadin
Treatment for coeliac’s disease
Withdraw Gluten
However, Wheat is used widely in commercial food manufacture
Diet is life long
MUST refer to a state registered dietitian
What are some other conditions that are associated with Coeliac’s disease (9)
Dermatitis herpetiformis
Type 1 DM
Autoimmune thyroid disease
Autoimmune hepatitis
Primary Biliary Cholangitis
Autoimmune gastritis
Sjogren’s syndrome - autoimmune disease that attacks glands that secrete tears + saliva
IgA deficiency
Down’s syndrome
Complications with coeliac disease (5)
Refractory coeliac disease - persistent or recurrent malabsorptive symptoms and villous atrophy despite strict adherence to a gluten-free diet
Small bowel lymphoma
Oesophageal carcinoma
Colon cancer
Small bowel adenocarcinoma
What is tropical sprue?
a malabsorption disease commonly found in tropical regions, marked with abnormal flattening of the villi and inflammation of the lining of the small intestine.
What is Giardia lamblie? How is it transmitted? Drug treatment used?
a unicellular parasite found in contaminated water
colonises and reproduces in the small intestine, causing giardiasis
responds to drug Metronidazole
What is Whipple’s disease?
rare bacterial infection common in middle aged men
Has skin, brain, joints and cardiac effects
It interferes with normal digestion and nutrient absorption
Tropheryma whippelii is the causative organism
weight loss and abdominal pain common
What is the hallmark of Whipple’s disease?
the accrual of periodic-acid Schiff (PAS)-stained foamy macrophages in the villi
Small bowel problems caused by medical examination/interference
Gastric surgery
Short bowel syndrome
Radiation
When can small bowel bacterial overgrowth occur?
in any condition that affects:-
Motility
Gut structure
Immunity
Treatment options for bacterial overgrowth?
rotating antibiotics:- - Metronidazole - Tetracycline - Amoxicillin Each for 2 weeks
vitamin and nutritional supplements too
Main causes of small intestinal problems in the UK
Chron’s
Coeliac disease
