malabsorption Flashcards
what are the clinical manifestations associated with fat malabsorption ?
steatorrhea
greasy foul smelling
stool floats
loss of fat soluble vitamins
what are the features of carbohydrate malabsorption ?
watery diarrhea
due to osmotic effect of sugar
what must be identified after we see that the diarrhea is watery ?
is it secretory or is it osmotic
secretory - cholera
osmotic - lactose intolerance
how can we differentiate between osmotic and secretory diarrhea ?
measure the osmotic gap
if the osmotic gap is large - >50 osmotic diarrhea
if the osmotic gap is low - <50 secretory diarrhea
what is celiac sprue ?
autoimmune condition associated with the destruction of the small intestinal villi
triggered by gluten exposure
what is the pathogenic component of gluten and what is needed to deaminate it ?
gliadin
that is deaminated by tissue transglutaminase
what is the immunological process associated with celiac disease ?
the deamidated gliadin is consumed by APC
presented to T cells
Type 4 hypersensitivity reaction
what is the genetic association with celiac disease ?
HLA-DQ2
HLA-DQ8
what are the histological features associated with celiac disease ?
blunting of the villi
crypt hyperplasia
lymphocytes in the lamina propria
what are the antibodies associated with celiac disease ?
anti gliadin
anti tissue transglutaminase
anti endomysial
what are the antibodies measured to detect celiac disease ?
IgA endomysial and tTG
what test is used for screening of celiac disease ?
IgA tTg automated
what is the order in which the test for the confirmation of celiac disease must be made ?
anti-tTG
IgA level
biopsy
which part of the GI tract is mostly affected by celiac disease ?
duodenum
what is the presentation of celiac disease ?
flatulence bloating , chronic diarrhea
steatorrhea
in children: failure to thrive
iron deficiency anemia
what are the complications associated with celiac disease ?
small bowel cancer - adenocarcinoma
T cell lymphoma (EATL)
what is the classic scenario associated with a celiac patient who develops an adenocarcinoma ?
patient adherent to gluten free diet with worsening symptoms
what dermatological condition is associated with celiac ?
dermatitis herpetiformis
what is the cause of dermatitis herpetiformis ?
IgA deposition in dermal pappillae
resolves with a gluten free diet
what is tropical sprue ?
malabsorption due to unknown infectious agents
occurs in the tropics
has bluting of the villi
what is the difference between tropical sprue and celiac sprue ?
celiac most commonly affects the duodenum
tropical sprue affects the entire small bowel
and is associated with folate/B12deficiency
where is folate and b12 absorbed ?
in the jejunum and the ileum
what is the treatment for tropical sprue ?
antibiotics (tetracyclines)
folate supplementation
what is whipples disease ?
infection associated with t whippeli
gram positive rod
what are the four cardinal features associated with whipples disease ?
diarrhea
abdominal pain
weight loss
joint pains ( migratory arthalgia)
what are the other clinical features associated with whipples ?
hyperpigmentation
CNS involvement
endocarditis - culture negative
mesenteric lymphadenopathy
how is a diagnosis of whipples made ?
by biopsy -PAS positive foamy macrophages
what is the treatment for whipples ?
ceftriaxone
what is lactose digested by ?
brush border enzyme lactase
what is the pathology associated with lactose intolerance ?
problem with the enzyme lactase
usually due to lactase no persitence
what are the secondary causes of lactose intolerance ?
mucosal injury
bacterial overgrowth , viral infection, giardiasis
present as lactose intolerance after GI illness
how is a diagnosis of lactose intolerance made ?
often clear from history
lactose breath hydrogen test
lactose tolerance test
what diseases are associated with pancreatic insufficiency ?
cystic fibrosis
chronic pancreatitis
obstruction
how does bacterial overgrowth cause malabsorption ?
small intestine should be sterile
if not - present with bloating, flatulence or abdominal discomfort
what are the causes of bacterial overgrowth ?
1- altered motility - usually associated with diabetes or scleroderma
2- partial or intermittent obstruction , adhesions from previous surgeries
or crohns disease
what is the gold standard for the diagnosis of bacterial overgrowth ?
1- jejunal aspirate (gold standard)
2- lactulose test
what is a fecal fat test ?
stool is collected over 1-3 days
amount fat is measure
normal is less than 7
anything more is increased in fat malabsorption
what is the d-xylose test ?
tests carbohydrate absorption in the small intestine
after fasting, patient ingests D-xylose
no enzymes required for this only an intact mucosa
when do we see abnormal results in a d xylose test ?
whipples disease
celiac disease
what test is best to be used in chldren to detect undigested sugars ?
cliniest
