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Flashcards in Chronic Diarrhea Deck (19)
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osmotic diarrhea?

getting carbs down in colon where they don't belong

type of watery diarrhea

osmotic gap > 100, relieved by fasting, etc.

From carbohydrates (as in lactase deficiency, other disaccharidase deficiency, sorbitol ingestion, etc.); and poorly absorbed salts (Mg++,Al3+, etc).


Secretory diarrhea

type of watery diarrhea

osm gap < 50, interrupts sleep, etc.

** bile acids diarrhea!!
- neuroendocrine tumors (carcinoid, VIP, etc.),
- increased motility (postvagotomy, DM, meds, IBS),
- villous adenoma,
- microscopic colitis
** infections (Giardia, Cryptosporodiosis, Cyclospora, Cystoisosporiasis (eosinophilia), amebiasis, etc).


Niacin deficiency * TQ

3 Ds of diarrhea, dermatitis and dementia -

- in Carcinoid
Syndrome, tryptophan is shunted to serotonin and is not available for niacin production.


What causes steatorrhea?

Fatty diarrhea

1. Malabsorption (celiac, tropical sprue, short bowel, lymphatic obstruction, mesenteric ischemia, Tropheryma whipplei)

2. Maldigestion (pancreatic insufficiency, bile acid deficiency or deconjugation/bacterial overgrowth)


Inflammatory diarrhea

(blood and pus seen in diarrhea)

positive hemoccult and fecal leukocytes, painful, and may be febrile:

- infections (CMV, Herpes including Kaposi’s, E. histolytica, Balantidium coli (pigs)**, C. diff, Campylobacter, Aeromonas, Plesimonas, Mycobacteria, Shistosoma (eosinophilia),
-ischemic and radiation colitis,
-colon cancer


CD less than 100 cm of ileal involvement? TQ

liver able to keep
up with bile acid synthesis, so enough bile acid is being released for fat absorption.

the bile acid can be absorbed, but not all of it, thus there is still some getting into the colon

The bile lost to the colon produces a secretory diarrhea, so it needs to
be bound to control the diarrhea.

tx: add bile acid binding agents


CD w/ ileal involvement greater than 100 cm? TQ

not enough micelle
formation (steatorrhea)- there is just too much intestine involvment - so need low fat diet, vitamin replacement,
and medium-chained triglycerides.

tx: low fat diet

** this is malabsorption due to short bowel syndrome!!!


what does steattorhea give?

easy bruising
back pain (fat binds up calcium)

inability to absorb ADEK


what causes IBS? TQ

(post-infectious diarrhea)

Increased fecal serine
protease activity, probably from an altered fecal flora!

- diarrhea that occurs clearly after eating, with all other tests being negative


Kidney and Cholesteral Gall stones? TQ

d/t malabsorption syndrome (such as short bowel syndrome) where you see steatorrhea

oxalate kidney stones because FAs bind calcium which results in increased oxalate absorption.

In addition, cholesterol gall stones form because of the low bile acid pool.


IgA deficiency?

present with bronchitis, diarrhea (including Giardiasis), transfusion reaction


Celiac disease? TQ

IgA mediated disease

- see IgA deposited in bowel

- assoc. w/ dermatitis herpetiformis (IgA deposited in skin)

characteristics: diarrhea, steatorrhea, weakness, w/l, abdominal distension, vitamin deficiency

mucosal biopsy: villous atrophy w/ lymphocyte infiltration

- can result in steattorhea (can present as osteopenia and malabsorption syndrome)
or just occasional diarrhea

- can present w/ purpura, osteopenia, or osteoporosis

- order IgA tTG


More stuff on Celiac Disease? TQ

Extraintestional manifestations:
- elevated liver and pancreatic
- infertility or spontaneous miscarriages
- iron deficiency anemia
- peripheral neuropathy;
- diabetes type 1, Addisons,
- osteopenia.

Characteristics: diarrhea, steatorrhea, weakness, weight loss,
abdominal distention growth retardation, , vitamin deficiency.

Mucosal biopsy = villous atrophy and crypt hypertrophy with
lymphocyte and plasma cell infiltration.

Complications: osteoporosis (Vit D and Ca2+ malabsorption) and malignancy (B cell Lymphomas)

*** can develop B cell lymphoma because it involves HLA-D (involving CD4+ T cells) -> activates B cells


what does stool pH <5 in osmotic diarrhea show?

A stool pH < 5 usually indicates the presence of FFAs consisting of butyrates, acetates, and proprionates which are all organic anions produced when colonic bacteria carry out fermentation on fecal CHOs. Thus, a stool pH of 3.5 would point to excess CHOs and an osmotic diarrhea.


Bacterial overgrowth seen in Pernicious anemia?

Bacterial overgrowth gives a watery diarrhea from the osmotic load of unabsorbed CHOs ( proteases from the bugs destroy the brush border disaccharidases) arriving in the colon. The colonic bacteria carry out fermentation on these CHOs with the additional production of FFAs consisting of butyrates, acetates, and proprionates which are all organic anions that lower the pH of the stool content to less than pH 5.

The bacteria also consume B12 and other nutrients. In addition, the bacteria deconjugate bile acids. This results in malabsorption of fat with resultant steatorrhea from lack of micelle formation, and the subsequent parade of these deconjugated bile acids to the colon where they further irritate and produce a secretory diarrhea, in this case accounting for the increased stool volume.


how do you test for bacterial overgrowth?

d-(14C)xylose breath test

d-(14C)xylose breath test: gut anaerobes metabolize the oral
(14 C)xylose to 14CO2 which is measured in the expired air at 30 minutes if there is small intestonal bacterial overgrowth.

Can also do this test:
- Hydrogen breath test: Give 50 gm of lactose and measure
breath hydrogen. In 90 minutes will have > 20 ppm of hydrogen from bacterial metabolism in the colon. An earlier peak (30 minutes) will be seen in bacterial overgrowth.

** at both cases you get a peak at thirty minutes


multiorgan involvement: chronic diarrhea, arthralgias, lymphadenopathy, w/l, lethargy, CNS changes, parasthesias

Tropheryma whippelii

This can be ddx from MAI/MAC from acid fast stain (its acid fast negative ) - whereas all of them would be PAS positive macrophages


how to calculate osmolar gap?

2 x (stool Na + K+)= #

subract this number frm the measured stool osmolality

ex. Stool Na is 90 mmol/L with K of 50 mmol/L. Stool osmolality is 290 mOsm/kg.
2 x (90 + 50) = 2 x 140 = 280
290 – 280 = 10

** thus would be secretory diarrhea Osm gap <50


bile acid diarrhea?

secretory diarrhea
- results from less than 100 cm of ileal involvment w/ CD.
- liver is able to keep up with bile acid synth, but bile is lost to colon producing secretory diarrhea

(there is enough fat absorption, thus no steatorrhea, but bile is getting through to the gut causing water diarrhea)