Step I Diarrhea question

[DrPak]

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Great question from another forum:

2 year old boy who has been previously well presents with foamy diarrohea, vague upper abdominal discomfort and failure to thrive for 2 months. weight is on the 25 th percentile, stool test reveals steatorrhoea with fatty acid crystals, the most likely diagnosis is :

A. giardia lamblia
B. coeliac disease
C. cystic fibrosis
D. campylobacter jejuni
E. rotavirus infection
F. cryptosporidia
G. acute gasteroenteritis

 

[Idiopathic]

well, its celiac, because the boy was previously healthy. however, this is also a possible presentation for cf. however, i lean toward celiac, given the age group and no pulmonary complaints.

 

[felipe5]

i'd also lean towards celiac (aka coeliac....crazy brits) mainly b/c i'd expect a youngster that has CF to experience symptoms long before the age of 2.

 

[Idiopathic]

i'd also lean towards celiac (aka coeliac....crazy brits) mainly b/c i'd expect a youngster that has CF to experience symptoms long before the age of 2.

Well, its about the time you start getting all the refined flours, etc. in the diet and fat malabsorption/failure to thrive is a hallmark.

 

[Kashue]

Well, its about the time you start getting all the refined flours, etc. in the diet and fat malabsorption/failure to thrive is a hallmark.

Going to agree with Celiac disease as well. CF would have appeared earlier and they would have mentioned other symptoms ie lung infections, meconium ileus etc.

 

[mamitch4]

CF would have appeared earlier and they would have mentioned other symptoms ie lung infections, meconium ileus etc.

For this question, I am on board with the celiac dz., and I agree that for the USMLE we would most likely see the classic presentation of CF with lung symptoms. For a non-board exam setting, it's probably a good idea to remember that CF can be a very heterogenous disease with presentation anywhere from birth to many years later depending on the specific mutation of the chloride channel and environmental factors. Robbins has a good discussion on this.

 

[DrPak]

Nope, it's not celiac. Babies are given given gluten after around 6 months. Celiac disease would have shown up before 2 years of age. In fact, emedicine.com puts the age of presentation b/w 8-12 months.

It's a tricky question isn't it? 😀

 

[Idiopathic]

Well, then the answer is probably gonna be crypto, but I do not like this question. Celiac is very common, often diagnosed well after presentation (i.e. 2 or 3 years) and presents just like this. I guess they chose cryptosporidium.

 

[Kashue]

Well, then the answer is probably gonna be crypto, but I do not like this question. Celiac is very common, often diagnosed well after presentation (i.e. 2 or 3 years) and presents just like this. I guess they chose cryptosporidium.

Bad Q!

 

[exmike]

I vote NO for crypto, since it usually a cause of intractable watery diarrhea in severely immunosuppressed and is self-limiting in immunocompetent. As far as we know this kid is immunocompetent. I was also thinking CF or Celiac. How do we know the kid didn't just start eating gluten foods recently? Maybe he nursed for two years 😀

 

[TheFlash]

this has got to be celiac disease if we go by sheer probablity and buzzwording like "failure to thrive" compounded with the presentation around when a child is first introduced to gliadin in the diet (i.e. cereal). however, the lack of info in the stem (i.e. lack of a histo sample or ab/hla analysis) and the other tantalizing answer choices (don't you just wanna go with pancreatic insuff 2ndary to CF?!) make this a poor Q, IMO.

 

[DrPak]

Why would it be crypto? Crypto is found most commonly in immunocompromised people.

And cystic fibrosis? Well, CF would also appear a lot earlier than 2 years. Plus, there are no respiratory problems at all.

Like I said, gluten is introduced around 6 months of age. The child had a year an a half to present with it, but didn't. Sure, celiac disease can present late, but playing odds here, celiac would turn out to be less likely. There's something in the answers thats more likely to be correct than celiac disease.

 

[exmike]

Why would it be crypto? Crypto is found most commonly in immunocompromised people.

And cystic fibrosis? Well, CF would also appear a lot earlier than 2 years. Plus, there are no respiratory problems at all.

Like I said, gluten is introduced around 6 months of age. The child had a year an a half to present with it, but didn't. Sure, celiac disease can present late, but playing odds here, celiac would turn out to be less likely. There's something in the answers thats more likely to be correct than celiac disease.

Giardiasis can cause a chronic low grade diarrhea. It effaces the intestinal villi and causes fat and protein malabsorbption that could cause the failure to thrive in this youngster (and foamy diarrhea).

 

[velo]

CF doesn't have to present as a neonate, it can present in early childhood with these symptoms and still be a +/- classic presentation. I think this would be an atypical presentation for any of the other choices (celiac has a bimodal distribution, either right after glutens are added to the diet or in middle age)

at any rate, its a lousy question. Too many of those options could be the right one, real step one question would throw you another hint to help you out....baby seems salty, baby is in day care, babies uncle has a "wheat" allergy....something. I still say CF

oh so what's the deal OP, what was it and what was the explaination?

 

[DrPak]

Giardiasis can cause a chronic low grade diarrhea. It effaces the intestinal villi and causes fat and protein malabsorbption that could cause the failure to thrive in this youngster (and foamy diarrhea).

👍

 

[velo]

👍

ah is that it? I still say crappy question, but was "fatty acid crystals" supposed to tip us off?

 

[DrPak]

I agree it's a "lousy" question in the sense that it can be too close to call. But it does get you thinking about all the different diarrheas and how to distinguish them. It was a great way to revise the diarrheas for me, so I put the question up here.

Goljan does say that the boards can be really picky sometimes and push things just up to edge. He once mentioned a question where an 8 day old baby started bleeding from orifices (vitamin K deficiency). That's pushing it cuz newborns usually start producing their own Vitamin K by the end of the first week.

Anyway... it was just a bit of fun.

 

[DrPak]

ah is that it? I still say crappy question, but was "fatty acid crystals" supposed to tip us off?

I thought that the fatty acid thing was a distracter and was part-and-parcel of the steatorrhea. Any thoughts on this?

BTW, what's this about day-care? Which diarrhea is MC in day-care centers? I heard about a pneumonia that's associated with day care, but not diarrhea.

 

[lord_jeebus]

I thought that the fatty acid thing was a distracter and was part-and-parcel of the steatorrhea. Any thoughts on this?

BTW, what's this about day-care? Which diarrhea is MC in day-care centers? I heard about a pneumonia that's associated with day care, but not diarrhea.

Wouldn't rotavirus be the most common cause of day care diarrhea? (not steatorrhea of course, i figured you'd gone off-topic)

I've heard of giardia outbreaks in day care centers but it can't be that common.

 

[exmike]

Wouldn't rotavirus be the most common cause of day care diarrhea? (not steatorrhea of course, i figured you'd gone off-topic)

I've heard of giardia outbreaks in day care centers but it can't be that common.

Rotavirus is a watery diarrhea, and is self-limiting

 

[Idiopathic]

Rotavirus is the MCC of diarrhea in all children, especially day-care, and its actually a very high source of morb + mort. They also have a vaccine for it this year, although I dont think that will be testable.

This is a bad questions because celiac presents exactly the same way and you cant just assume that parents introduced gluten into the diet at 6 months and that the childs symptoms were subclinical before. Giardiasis is definitely not the best answer choice

BTW, "Cryptosporidium, another parasitic organism, is also a frequent cause of gastrointestinal illness in children. It's commonly involved in diarrhea epidemics in child care centers." (from kidshealth.org). it does mention giardia as more common than crypto, but i would imagine not by much.

 

[velo]

the buzzword-y association I see a lot is giarda with daycare. You could have a rotavirus outbreak at daycare as well but it wouldn't last 2 months

 

[Idiopathic]

the buzzword-y association I see a lot is giarda with daycare. You could have a rotavirus outbreak at daycare as well but it wouldn't last 2 months

i agree this scenario is not rotavirus. wouldnt you at least expect them to tell you the child went to day care? you know going to day care is actually not the most common scenario. most kids stay at home.

 

[DMBmatty08]

I thought that the fatty acid thing was a distracter and was part-and-parcel of the steatorrhea. Any thoughts on this?

BTW, what's this about day-care? Which diarrhea is MC in day-care centers? I heard about a pneumonia that's associated with day care, but not diarrhea.

The fatty acid crystals could be present due to inadequate lipase production by the pancreas. This could be caused by thick mucus of CF blocking the passage of pancreatic enzymes into the intestines. Thus the fat does not get broken down and crystalizes.

 

[Idiopathic]

The fatty acid crystals could be present due to inadequate lipase production by the pancreas. This could be caused by thick mucus of CF blocking the passage of pancreatic enzymes into the intestines. Thus the fat does not get broken down and crystalizes.

Steatorrhea and fatty acid crystals would be seen in the first four conditions, so its impossible to go off that, except to rule out rota, campy, etc.

 

[DrPak]

Well, fat and fatty acids are not the same thing. The latter is a component of the former.

Actually... come to think of it, I believe the fatty acid crystals thing signified that digestion of fats did take place, thereby ruling out CF. Anyone concur?

 

[beastmaster]

Crypto is self-limited and rarely lasts over a month. The failure to thrive and foamy rules out infectious causes because they question asks "most likely."

This is a fat malabsorption.

 

[Idiopathic]

Well, fat and fatty acids are not the same thing. The latter is a component of the former.

Actually... come to think of it, I believe the fatty acid crystals thing signified that digestion of fats did take place, thereby ruling out CF. Anyone concur?

I do not concur. Remember, CF patients dont knock off their entire pancreas, they just lose lots of function. Some digestion will take place, and there will be lots of malabsorption = FA crystals. I believe its seen in most malabsorption states.

 

[beastmaster]

J Hyg (Lond). 1981 Oct;87(2):313-9. Related Articles, Links


Virus diarrhoea associated with pale fatty faeces.

Thomas ME, Luton P, Mortimer JY.

Steatorrhoea was a significant feature in an outbreak of rotavirus gastroenteritis which affected adults and infants in hospital. Fat globules or fatty acid crystals were obvious by light microscopy (LM) in faeces from 14 of 25 patients examined. Ten of the fatty stools and two of the remainder were very pale. By electron microscopy (EM) a rotavirus was seen in 11 of the 14 fatty faeces and in only two of 11 specimens without visible fat. In a further study of pale or fatty faeces 20 such specimens sent for laboratory examination from patients not involved in the hospital outbreak were compared microbiologically with a similar number which were neither pale nor fatty. Viruses were found by EM in 11 (55%) of the pale or fatty stools; eight rotaviruses, two astroviruses and an uncultivable adenovirus were seen; one further patient had acute jaundice. In contrast, no viruses were seen by EM in the twenty specimens which were normally pigmented and without evident fat. Steatorrhoea was significantly associated with rotavirus infection of the alimentary tract which usually presented as a fatty enteritis. We conclude that rotaviruses certainly, and other viruses possibly, can impede both the digestion of fat and the pigmentation of the faeces. Inspection and LM of faeces are easy. In acute enteritis a fatty or pale stool is an indication for virological examination.

PMID: 6270209 [PubMed - indexed for MEDLINE]

(not the answer though)

 

[Idiopathic]

there you go, even your secretory rota squirts can give you malabsoprtion of fats.

edit: but rota is more self-limiting than this clinical pic.