Lower GI Tract Flashcards
Difference between malabsorption and maldigestion vs malassimilation
Defective mucosal uptake and transport of adequately digested nutrients vs impaired breakdown of nutrients(mainly in the small intestine), lumenal phase (eg pancreatic insufficiency).
Malassimilation refers to both
What is Zollinger- Elison syndrome
When tumours overproduce gastrin and therefore gastric acid, affecting functions of enzymes
What problems can affect fat solubilization
Decreased bile salts due to cholestasis or cirrhosis
Bile salt loss due to resection of ileum
Bile salt deconjugation due to bacterial overgrowth
What can affect Lumenal availability of nutrients and what nutrient in particular
- Bacterial consumption of nutrients (bacterial overgrowth) ⇒ B12 deficiency
- Decreased intrinsic factor (pernicious anaemia) ⇒ B12 deficiency
What are common causes of distruption of epithelial transport?
Damaged absorptive surface due to inflammatory diseases like coeliac’s or tropical sprue, Crohn’s. Or ischaemia
Infections like Giardia or SIBO
Lymphoma or amyloid infiltration
What is a post- mucosal cause of malabsorption
Problem with post-absorptive processing eg. lymphatic obstruction which affects fat transport. Neoplasms, TB and lymphangectasia are examples.
What are the clinical features of malabsorption
- Diarrhoea and weight loss despite adequate intake
- Bloating, tense abdomen, distention, cramps, borborygmi ⇒ Abnormal fermentation of nutrients by bacteria in colon
- Lethargy, malaise
- Symptoms often mild, non-specific
- Malabsorption can be global, or specific nutrients
- Malabsorption syndrome
What is malabsorption syndrome
steatorrhoea, distention, weight loss, oedema is a RARE presentation
What is a symptom of vascular insufficiency in gut
ntestinal angina
–Abdominal pain after a meal due to vascular insufficiency in gut ( which can also cause malabsorption)
What is one genetic disease that can cause malabsorption
Cystic fibrosis
What skin condition is associated with Coeliac’s
Dermatitis hepertiformis
What are the neurological symptoms of B12 deficiency
- Peripheral neuropathy
- Ataxia (posterior column) ⇒ Spinal cord damage
- Psychosis, dementia
What does microcytosis in malabsorption suggest
iron deficiency (common in coeliac, otherwise suspect GI blood loss)
What does macrocytosis in malabsorption suggest
B12 and folate deficiency( due to malabsorption??), but also common in coeliac, alcohol
What does elevated ALP in malabsorption suggest
Signs of metabolic bone disease, due to Vit D malabsorption
What are the tests for the three most commonest causes of malabsorption
- Tissue Transglutaminase (TTG) ⇒ Antibody test Coeliac disease
- Faecal elastase ⇒ Enzyme measurement in stools for Pancreatic enzyme insufficiency
- Glucose H2 breath test ⇒ SIBO
How to test for IBD
Faecal calprotectin
How to test for Bile acid malabsorption
7alpha-cholestenone or SeHCAT test ( for retention)
How to test for lactase deficiency
Lactose H2 breath test
causes of strictures in small bowel and what imaging is done for it
MRI ⇒ May find strictures which could be ischaemic, Crohn’s, Neoplastic, TB etc.
use of CT/ CT angiogram in lower GI
pancreatic disease, mesenteric ischaemia
What are causes of PEI
Chronic pancreatitis => alcohol is most common cause
May be autoimmune
Duct obstruction
Cystic fibrosis that causes thick sticky mucus that clogs the pancreatic ducts
SLE
Autoimmune pancreatitis
- Haemochromatosis ⇒ Rare- abnormal iron deposition in liver and pancreas
- Pancreatic resection ⇒ For cancer or pancreatitis
- Gastric resection ⇒ Can cause changes in acidity and impair enzyme function
Absorption of what nutrient gets affected first in PEI
fat
Symptoms of PEI
Steatorrhea, weight loss, vitamin deficiency (A,D,E,K), also more `minor symptoms
How to diagnose PEI
- Pancreatic imaging (CT, MRI)
- Tests of exocrine pancreatic function
- Direct – eg Secretin stimulation tests ⇒ stimulates pancreatic secretions (sensitive but cumbersome)
- Indirect
- Faecal elastase is the most common ⇒ samples level of enzymes in stool . Not sensitive
- Pancreolauryl (only reliably detect moderate to severe PEI)
Treatment of PEI
- Pancreatic enzyme replacement
- Taken with meals and snacks
- Gastric acid suppression since pancreatic enzymes require higher pH
- Vitamin supplements
Are bacteria in ileum and colon gram positive or negative
Mostly gram negative in ileum, +ve in colon
What happens in SIBO
Bacteria from colon moves to SI and ferments food higher up in the gut
What are the causes of bacterial overgrowth
- Stasis
- Strictures (crohn’s, TB)
- Hypomotility ( old age, opiates, diabetes etc.)
- Blind loops, Diverticulae (pockets in wall of small intestine)
- Immunodeficiency ⇒ Cancer drugs, immunosuppresants eg. in Crohn’s
- ?Obesity
Gold standard of diagnosing SIBO and what is more commonly done in practice. What else can be done?
Aspiration of jejunal fluid and quantitative culture
Glucose/Hydrogen breath test more practical => Higher hydrogen in SIBO
Can use MRI to check for strictures
Treatment for SIBO
- Treatment with 2 weeks of antibiotics e.g. tetracycline(systemic), ciprofloxacin, rifaximin (non-absorbed ideally)
- Often needs repeat treatment especially for blind loop or stagnant loop
What can cause hypomotility in gut
- Old age
- Immune compromise
- Opiate analgesics ⇒ slow transit of food through the gut
- Diabetes
- Systemic sclerosis
How dose giardiasis cause malabsorption
- Malabsorption due to multiple factors
- Brush border damage
- Reduction in absorptive surface
- Bile acid utilization
- Induction of hypermotility
- Enterotoxin
How to investigate/ diagnose giardiasis
Stool samples, but may need microscopy
Treatment of choice for giardiasis
Metrionidazole
Where are bile acids specifically absorbed in??
distal ileum
What kind of diarrheoa does bile acid malabsorption cause
Secretory diarrhoea
What causes BAM
- Affected by (terminal) ileal disease, Crohn’s disease or resection of terminal ileum
- Also impaired in post- cholecystectomy, rapid transit and other malabsorptive states
What are the main types of BAM
- Type 1 ⇒ Ileal disease or resection
- Type 2 ⇒ Idiopathic
- Secretory diarrhoea from bile acids in colon
- Type 3 ⇒Assoc with cholecystectomy, rapid transit, coeliac, SIBO, chronic pancreatitis
- Cholecystectomy ⇒ Bile is being delivered in constant trickle rather than bolus after a meal , results in wasting of bile salts⇒ may cause diarrhoea but may not be severe enough to cause lipid malabsorption
Treatment for BAM
- Cholestyramine
- Colesevelam
What is Whipple’s disease
- Uncommon bacterial infection in older men
- Caused by Tropheryma whippleii ( found in tropics)
presentation of whipples
- Presents with diarrhoea, arthritis, fever, cough, headache, muscle weakness
Treatment of Whipple’s
Antibiotic therapy for months to years.
What can IBS be due to
- Over or underactivity of the gut
- Brain- gut interaction
what neurotransmitter is involved in communication between myenteric and submucosal plexus
5HT
Common history and presentations of IBS
May have had gastroenteritis before start of symptoms
Abdominal symptoms, may be colicky pain post prandial, urgent need to move bowels with diarrhoea and mucus ( also post-prandial), but may have tenesmus and sense of incomplete evacuation.
ALternating diarrhoea and constipation
Bloating and discomfort, distention
Rome IV criteria for IBS
- Abdominal pain
AND - 2 of:
- Related to defaecation
- Change in stool frequency
- Change in stool form
- Symptoms over 6/12, on average weekly for last 3/12
What is the threshold for classification of IBS
25% of BM
investigations in IBS
FBC, ESR,UnE,LFT,TFTetc.
ESR for markers of inflammation
TTG for coeliac
Stool for microscopy and culture
Faecal calprotectin maybe, for IBD
Abd ultrasound for gallstones
Common associations in IBS
Migraine, dyspepsia, dyspareunia, bladder problems, fibromyalgia, chronic fatigue
When is diarrhea more likely for IBS
Morning, if nocturnal may need to exclude other causes
Red flag symptoms for IBS
- Weight loss
- Rectal bleeding,
- Anaemia, thrombocytosis
- Persistent diarrhoea (lack of day-day variability)
- New onset over 50 yrs
- Frequent nocturnal symptoms
- FHx bowel cancer/IBD
Management of IBS
Lifestyle - Dietary, low FODMAP, restrict lactose and gluten
drug therapy
Drug- based on symptoms
Psychological - CBT, hypnotherapy
Drug management of IBS
Antispasmodic- peppermint oile, TCA very useful for pain ( amitriptyline), loperamide useful for diarrhoea, ispaghula cor constipation, macrogol also as a laxative
What arteries supply transverse colon
SMA and IMA, anatomical variations
Consequences of SIBO
- Vitamin B12 malabsorption
- Bile acid deconjugation ⇒ Relative bile salt deficiency, affects fat absorption
- Intraluminal protein utilization
- Brush border damage
- Ulceration of mucosa ⇒ inflammatory
- Bowel dysmotility
What type of mucosa exists in the rectum
Squamous, instead of columnar
