Malabsorption Flashcards
what is malabsorption?
= defective mucosal absorption which is caused by;
(i) defective luminal digestion
(ii) mucosal disease
(iii) structural disorders
what are some common and uncommon causes of malabsorption?
Common
- coeliac disease
- Crohn’s disease
- post infection
- biliary obstruction
- cirrhosis
Uncommon
- pancreatic cancer
- parasittes
- bacterial overgrowth
- drugs
- short bowel
what are 4 states of malabsorption?
- protein
- fat
- carbohydrates
- vitamins & minerals
what are the digestive and absorptive causes of protein malabsorption?
Digestive
- gastrectomy (poor mixing)
- exocrine pancreatic insufficiency
- trypsinogen deficiency
- congenital intestinal enterokizase deficiency
Absorptive;
- coeliac disease & tropical sprue
- short bowel syndrome
- jejunoileal bypass
- methionine malabsorption syndrome & blue diaper syndrome
- defects in neutral AA transporters
- cystinuria I-III
- oculocerebral syndrome of Lowe
what are the digestive, absorptive and post absorptive causes of fat malabsorption?
Digestive;
- less time to mix gastric resection, autonomic neuropathy, amyloidosis
- dec micelle formation, decreased bile acid synthesis/secretion, cirrhosis, biliary obstruction, CCK deficiency, small intestinal bacterial overgrowth
- decreased lipolysis, chronic pancreatitis, cystic fibrosis,, pancreatic/ampullary tumours, low luminal pH, excessive calcium ingestion, lipase/co-lipase defieicny
Absorptive
- decreased chylomicron formation & mucosal absorption, coeliac disease, abettalipoproteinemia, hypobetalipoproteinemia, chylomicron pretension disease
Post-Absorptive
- defective lymphatic transport, primary intestinal lymphangectasis, lymphoma, Whipple disease, trauma, retro-peritoneal fibrosis
what are the digestive and absorptive causes of carbohydrate malabsorption?
Digestive;
- severe pancreatic insufficiency (alpha amylase def)
Absorptive = primary or acquired lactase deficiency - post infectious lactase deficiency - coeliac disease - crohn's disease - sucrase isomaltase deficiency - trehalase deficiency
describe the things that lead to vitamin B12, folic acid and fat soluble vitamins malabsorption? (vitamins)
Vitt B12 (cobalamin)
- atrophic gastritis
- deficiency of gastric intrinsic factors
- pancreatic insufficiency/Z-E syndrome
- helminth infections/SI BO
- leal crohn’s disease/resection
Folic acid;
- diseases affecting Proxima small bowel
- coeliac disease/whipple/tropical sprue
- alcoholism
Gat soluble vitamins (ADEK)
- anteing disrupting fat absorption will result in one or more deficiency
what causes calcium, magnesium, iron, zinc and copper malabosption? (minerals)
Calcium;
- renal disease/hypoparathyroidism
- inborn defect in Vit D receptor or 1alpha,25-dihydroxy vitamin D formation
- diseases that reduce intestinal surface area and/or cause formation of insoluble calcium soaps with long chain fatty acids (coeliac disease/bile acid deficiency)
Magnesium;
- caused by loss of mucosal surface area and/or luminal binding my malabsorbed fatty acids
Iron;
- caused by reduced mucosal surface area, but most often caused by GI bleeding
Zinc;
- acrodermatitis enteropathica
Copper;
- menkes disease, caused by inherited disorder of cellular copper transport
what are 5 specific disease states?
1) coeliac disease
2) whipple’s disease
3) crohn’s disease
4) parasitic infections
5) small bowel bacterial overgrowth
what is coeliac disease?
= exposure to wheat, barley, rye inducing a characteristic mucosal lesion
what causes coeliac disease?
- intestinal antigen presenting cells in people expressing HLA-DQ2 or HLA-DQ8 bind with dietary gluten peptides in their antigen binding grooves activating specific mucosal T lymphocytes cytokines mucosal damage
what are symptoms if coeliac disease?
- spectrum asymptomatic to nutritional deficiencies
- weight loss
- diarrhoea
- excess flatus
- abdominal discomfort
how would you diagnose and treat coeliac disease?
Diagnosis
- IgA anti-tissue transglutaminase test (tTGA)
- biopsy confirmative
Treatment;
- gluten free diet
what causes lactose malabsorption?
= deficiency of lactase
what are the symptoms of lactose malabsorption?
- diarrhoea
- abdominal discomfort
- flatulence
= following ingestion of dairy productions
how would you diagnose and manage lactose malabsorption?
Diagnosis
- confirmed by lactose breath hydrogen test
- oral lactose intolerance test
Management;
- lactose free diet
what is tropical sprue?
disease of small intestine causing malabsorption of food
what causes tropical sprue?
- colonisation of intestine by an infectious agent or alterations in intestinal bacterial flora induced by exposure to another environmental agent
what are the symptoms of tropical sprue?
= diarrhoea = steatorrhea = weight loss = nausea = anorexia = anaemia
how would you diagnose and treat tropical sprue?
Diagnose
= biopsy
treat
= tetracycline
+ folic acid
what is Whipple’s disease?
rare bacterial infection affecting joints and digestive system
what causes whipple’s disease?
= tropheryma whipplei
(multi system involvement)
+ increase iii frequency of HLA-B27
what are the symptoms of whipples disease and how would you diagnose and treat it?
Symptoms
- weight loss
- diarrhoea
- steatorrhea
- abdominal distension
- arthritis
- fever
- nutritional def symptoms
Diagnosis
- demonstration of T. whipplei in involved tissue by microscopy
Treatment
= anti-microbial
what is Crohn’s disease?
a chronic inflammatory disease of the intestines, especially the colon and ileum, associated with ulcers and fistulae
when do people with Crohn’s disease develop malabsorption?
In patients with; - extensive ileal involvement - extensive intestinal resections - enterocoelic fistulas - strictures = leading to small intestinal bacterial overgrowth causing malabsorption
what are symptoms of Crohn’s disease?
- abdominal pain
- diarrhoea
- fever
- weight loss
- abdominal tenderness (most classically right lower quadrant = RLQ)
how would you diagnose and treat Crohn’s disease?
Diagnosis;
- endoscopy
- barium imaging of small bowel mucosal disease incising strictures, ulcerations and fistulae
- CT
- MRI
- colonoscopy = punched out lesions
Treatment;
- steroids
- immuno-suppressants
- azatiopkinne 6-MP
- biological therapy (anti-TNF)
give an example of a parasitic infection that could arise? and other examples of parasites.
= giardia lamblia
- coccidial
- strongyloides
what are the risk factors for developing giardia lamblia ?
- travelling to areas where water supply may be contaminated
- swimming in ponds
what are the symptoms of giardia lamblia?
- diarrhoea
- flatulence
- abdominal cramps
- epigastric pain
- nausea
+ malabsorption
+ steatorrhea
+ weight loss
how would you determine if you have a giardia lamblia infection?
= stool examination for ova and parasites, 3 separate stool samples increases the yield of positive examinations
how would you teat giardia lamblia ?
= metronidazole - 1 week
what causes small bowel bacterial overgrowth?
- diarrhoea
- steatorrhea
- macrocytic anaemia (B12)
- E. coli and bacteroids
- diverticula
- fistulas
- strictures related to crohn’s disease
- bypass surgery functional stasis
how would you diagnose small bowel bacterial overgrowth in a lab?
- low cobalamin and high folate levels
= aerobic and/or anaerobic colonic-type bacteria in jejunal aspirate obtained by intubation.
= bacterial overgrowth is best established by a schilling test
how would you treat small bowel bacterial overgrowth ?
= surgical correction of an anatomical blind loop
- tetracyclines 2-3weeks
what 6 things should you focus on in diarrhoea?
- duration
- malabsorbtive stool
- fat globules
- floating
- hard to flush away
- offensive
describe the 2 important skin conditions you can acquire as a result of malabsorption?
= acrodermatitis enteropathica
- autosomal recessive
- impaired zinc uptake
- rash, perineal, aural, alopecia
- life long zinc supplement
= dermatitis herpetiformis
- may indicate coeliac disease
- itchy bilsters
- extensor surfaces
- sub-epithelial IgA deposition
what are 6 baseline investigations that would be done in malabsorption?
- FBC
- coagulation
- LFTs
- albumin
- calcium/magnesium
- stool culture
what are anatomical investigations that can be done?
- endoscopy
- imaging
