Small intestinal disorders and investigations Flashcards
What is digestion?
Breaking down of food into its components
What is absorption?
Passage of nutrients into the body
what are barrier functions?
Regulating what stays in and gets out
what are endocrine and neuronal control functions of the small intestine?
Controlling the flow of material from the stomach to the colon
Motility
What are the functions of the small intestine?
Digestion
Absorption
Endocrine and neuronal control (flow of material from stomach to colon)
Barrier functions
When is the full length of the small intestine reached?
Usually by age 11
what are the functions of digestion?
Decontaminates dirty food
Requires a lot of fluid
Controlled hydrolysis to avoid fluid shifts
Sophisticated control of motility
Absorption against gradients
Onward processing in the liver
where does digestion commence?
in the stomach
what causes digestion in the stomach?
Salivary amylase
Pepsin
Controlled breakdown to avoid osmotic shifts
how are proteins digested?
Broken down to oligopeptides & amino acids
Trypsin, chymotrypsin
Final hydrolysis and absorption at brush border
where does final hydrolysis and absorption of proteins occur?
brush border
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 allows the small intestine to have such as large surface area?
Villous architecture
Constant turnover of cells in crypts and villi
Why does the small intestine have a low bacterial population?
Toxic environment due to digestive enzymes, bile salts and IgA
What does maintaining control of digestion require?
Lots of fluid
Controlled hydroplysis to avoid fluid shifts
Sophisticated control of motility
Absorption against gradients
Onwards processing in the liver
What enzymes are in the stomach for digestion?
Salivary amylase
Pepsin
Why must digestion in the stomach be controlled?
Avoid osmotic shifts
What are proteins broken down into?
Oligopeotides and amino acids
What enzymes control the breakdown of protein?
are there many small bowel investigations that are tests of structure?
many and various
are there many small bowel investigations that are tests of function?
very few
what are the tests of structure available for the small intestine?
Small bowel biopsy
Endoscopy
CT Scan
MRI enterography
Capsule enterography
what is capsule enterography?
Capsule endoscopy is a procedure that uses a tiny wireless camera to take pictures of your digestive tract. A capsule endoscopy camera sits inside a vitamin-size capsule you swallow. As the capsule travels through your digestive tract, the camera takes thousands of pictures that are transmitted to a recorder you wear on a belt around your waist.
what are other assorted tests of the small intestine?
Bacterial overgrowth
H2 Breath test
Lactulose or glucose substrate
Culture a duodenal or jejunal aspirate
What enzymes control the breakdown of protein?
Trypsin and chymotrypsin
What enzyme controls the breakdown of fat?
pancreatic lipase
What is fat broken down into?
Glycerol and free fatty acids
What enzyme controls carbohydrate breakdown?
Pancreatic amylase
What does pancreatic amylase break carbohydrates down into?
Disaccharides
What does the final digestion of carbohydrates?
Brush border disaccharidase
What are symptoms of small intestine disorders?
Weight loss
Increased appetite
Diarrhoea
Sometimes steatorrhoea
Bloating
Fatigue
What is steatohoea caused by?
Fat malabsorption
What is poo like for someone who has steatorrhoea?
High fat content
Stool less dense and floats
Pale
Foul smeeling
May leave an oily mark or oil droplets
What are signs of small intestinal disorders?
Signs of weight loss such as low or falling BMI
What are some examples of possible vitamin/mineral deficiencies?
Iron
B12
Ca2+, Mg2+
D
B9 (folate)
A
K
B complex
C
What is a sign of vitamin A deficiency?
Night blindness
What is a sign of vitamin K deficiency?
Raised PTR
What are signs of thiamine deficiency?
Memory, dementia
What are signs of niacin deficiency?
Dermatitis, unexplained heart failure
What is a sign of vitamin C deficiency?
scurvy
What is clubbing a sign of?
Coeliac disease
Crohn’s disease
What is scleroderma a sign of?
Systemic sclerosis
What is aphthous ulceration a sign of?
Coeliac disease
Crohn’s disease
What is dermatitis herpetiformis?
Cutaneous manifestation of coeliac disease:
blistering
intensely itchy
scalp, shoulders, elbows, knees
IgA deposits on skin
how common is coeliacs disease?
1:111 in UK on screening data
1:300 clinical diagnosis
what are tests done for coeliacs disease?
Serology
IgA/IgG tests - IgA more reliable than IgG, only if you make IgA a significant amount of people dont
ALWAYs check plasma IgA aswell
how common is selective IgA deficiency?
Selective IgA deficiency is relatively common, about 0.1 to 1% of population
But 2 to 3% of coeliacs
Are IgA or IgG tests more reliable?
IgA
Who often has selective IgA deficiency?
Coeliacs (3%)
What are confirmational tests for coeliac disease?
Distal duodenal biopsy (looking for villous atrophy and HLA status)
what are the different types of villous atrophy?
Partial
Subtotal
Total
What is coeliac disease?
Autoimmune disease where the small intestine becomes inflammed
What is gliadin?
Class of proteins present in wheat, rye and barley
What is gliadin a component of?
gluten
What is the pathology of gliadin in people with Coeliac disease?
Produces an inflammatory response
Partial or subtotal villous atrophy
Increased intra-epithelial lymphocytes
What is done to diagnose people allergic to gliadin
Distal duodenal biopsy
Serology (anti endomysial IgA, anti-tissue transglutaminase)
is gliadin in rice, maize or oats?
no
Though what tissue does gliadin produce an inflammatory response through?
Thought to be transglutaminase
what are 97% of coeliacs for their HLA status?
either HLA DQ2 or DQ8
What is the treatment for people allergic to gliadin?
Withdraw gluten
Refer to state registered dietitian
What are some associated conditions with gliadin allergy?
Dermatitis herpetiformis
IDDM
Autoimmune thyroid disease
Autoimmune hepatitis
Primary Biliary Cholangitis
Autoimmune gastritis
Sjogren’s syndrome
IgA deficiency
Down’s Syndrome
What are some complications of gliadin allergy?
Refractory coeliac disease
Small bowel lymphoma
Oesophageal carcinoma
Colon cancer
Small bowel adenocarcinoma
What are different categories of causes of malabsorption?
Inflammation
Infection
Infiltration
Impaired motility
Iatrogenic
Pancreatic
What are some diseases that cause malabsorption through inflammation?
Coeliac disease
Crohn’s disease
What are some infections that can cause malabsorption?
Tropical sprue
HIV
Giardia lamblia
Whipple’s disease
what is giardia lamblia?
Unicellular parasite
Contaminated water
Responds to Metronidazole
Hypogammaglobulinaemia
What is an infiltrative cause of malabsorption?
amyloid
What are diseases that can cause impaired motility leading to malabsorption?
Systemic sclerosis
Diabetes
Pseudo obstruction
What are some iatrogenic causes of malabsorption?
Gastric surgery
Short bowel syndrome
Radiation
What are some pancreatic causes of malabsorption?
Chronic pancreatitis
Cystic fibrosis
who does whipples disease most commonly affect?
middle aged men
what does whipples disease affect?
skin, brain,joints, cardiac effects
what are symptoms of whipples disease?
Weight loss
Malabsorption
Abdominal pain
what is the causative organism of whipples disease?
Tropheryma whippelii is the causative organism
Small bowel overgrowth can occur in any condition that affects what?
Motility
Gut structure
Immunity
What is small bowel overgrowth diagnosed by?
H2 breath test
What is the treatment for small bowel overgrowth?
Rotating antibiotics
what are the rotating antibiotics examples, how long should they each be taken for?
Metronidazole
Tetracycline
Amoxicillin
each for two weeks
what should be taken alongside rotating antibiotics?
Vitamin and nutritional supplements
77 year old man
Losing weight
Steatorrhoea
Recent minor fall with fractured neck of femur
Radiologist notes features of osteomalacia
what is this man suffering from?
Tests confirm
Fat malabsorption
Bacterial overgrowth
Small bowel study
Multiple jejunal diverticula
23 year old student
Tired
? Losing a little weight
Variable stool
Bloating
PMH
Irritable Bowel Syndrome
On Examination
Thin
BMI 20 kg / m2
what is this student suffering from?
Hb 108
MCV 79
A microcytic anaemia
Alb 34
Very slightly reduced
Corrected Ca2+ 2.05 mmol/l
? Coeliac disease
Anti tissue transglutaminase (Anti-TTG) IgA negative
[Anti endomysial antibody neg]
Plasma IgA 0.1
