So what about a patient with diarrhea?
The definition of diarrhea is more than 10 ccs
per kilo per day of fluid loss through stools.
That might be on a test.
I find it fairly useless in terms of a definition.
Mostly because it’s almost impossible to measure
how many ccs per kilogram per day of stool is coming out of a child.
The leading cause of death worldwide
in terms of morbidity and mortality in children is infectious diarrhea.
Rotavirus is a killer in the developing world.
In the United States, much less common
because we have a medical system where
children can come and get help if they’re feeling dehydrated.
Generally, we will define diarrhea as acute or chronic.
The vast majority of diarrhea is acute
and it is less than two weeks prior to presentation.
If a patient has more than two weeks of duration of diarrhea,
we will call that chronic,
and we’ll go through in a bit what the differences are
in terms of etiologies of these various types of problems.
So let’s go through types of diarrhea
because this is important to understand and can sometimes show up on exams as well.
Secretory diarrhea is when intestinal epithelial cells
are actively secreting water into the intra-intestinal compartment.
And electrolytes are going along with it
and through osmotic forces are causing water loss out into the stools.
The classic example here is cholera toxin.
It is extremely rare to encounter secretory
diarrhea in children in developing countries.
Osmotic diarrhea is much more common.
This is generally because of ingested solutes,
which are poorly absorbed causing water to get
extruded into the intestinal compartment and then stooled out.
An example of this is a child who drinks too much juice.
Unfortunately, we see this a lot.
We sometimes even see children who are failing to thrive
because of excessive juice consumption.
So, children who eat large amounts of osmotic material will start to stool out.
Motility disorders can occur occasionally happen which can decrease transit time.
Generally, this is through bacterial overgrowth.
This is not too common.
Lastly, and especially in children with things like short gut syndrome,
patients may have decreased surface area,
and thus, an inability to actually absorb material
creating what is effectively an osmotic diarrhea.
Short gut syndrome is really common in some of our NICU graduates,
especially those who have made it through an
experience of surgical necrotizing enterocolitis.
So let’s drill down into the causes of acute diarrhea.
By far and away, the most common cause is infectious.
And among infectious causes, by far and away, the most common is viral etiologies.
Viral illness used to be more in the spring with rotavirus outbreaks.
That’s less common now because of the vaccination that we do.
So, it now tends to be a little bit more in the summer,
and perhaps, into the fall as well.
And of course, in the winter, we see some viral gastroenteritis as well.
Bacterial etiologies are not uncommon.
We see Campylobacter, E. coli, Salmonella, Shigella, even Yersinia.
And all of these can cause bloody stools.
In patients who have been exposed to antibiotics, you may see C. difficile.
There may be systemic infections that are causing children to have acute diarrhea,
especially younger children who may just have
that as a response to their general infection.
And parasites are possible although more common in developing countries.
In older children, you may see that with food poisoning.
Although with food poisoning, which is ingestion of a preformed toxin
rather than the actual bacteria causing the problem,
more commonly, patients have vomiting as well.
There are, of course, noninfectious causes of acute diarrhea.
Antibiotic associated diarrhea is common with some antibiotics
such as amoxicillin/clavulanic acid,
which may cause diarrhea in up to 40% of the patients who are taking the drug.
Hirschsprung toxic colitis is an unusual but important condition to know about.
I say noninfectious because the patient has an
underlying problem with Hirschsprung disease,
as you recall, and there is another lecture on Hirschsprung.
Patients will have a lack of ganglions in their rectal muscular tissue
which causes them to be tonically constricted and get constipation.
However, if these patients get diarrhea,
an acute viral gastroenteritis or bacterial gastroenteritis,
they can get very, very sick because the diarrhea has a hard time getting out,
and bacteria can invade the intestinal wall,
and these patients can go into shock.
Neonates, and we’re seeing more of this than ever before,
are exposed to opium or opiates in utero.
And as they come out, diarrhea is a common result of withdrawal from opiate exposure.
Patients with congenital adrenal hyperplasia will often have diarrhea at birth.
In older children, we again see the antibiotic-associated diarrhea.
Appendicitis may cause diarrhea
but it’s more common there to have vomiting and abdominal pain.
Chronic diarrhea can also cause problems in children
although it’s much less rare than acute diarrhea.
Examples in both infants and older children
include parasites and abscesses around the appendix,
as in an old perforated appendix
that’s healed up and they have some residual diarrhea leftover.
Patients may have malabsorption problems.
And again, this will cause more of that osmotic diarrhea.
So examples would be post-infectious.
After their diarrhea, children can rub off the lactase in their intestinal wall
and be translated lactose intolerant.
Patients can have food protein intolerance or allergy.
Children can get cystic fibrosis, Celiac disease, toddler’s diarrhea.
In older children, we do see true lactose intolerance
even though that’s much rarer in the younger children and infants.
Adolescents who are trying to lose weight inappropriately may use laxatives.
Celiac disease and very, very rarely secretory neoplasms
can cause a secretory diarrhea.
Of course, autoinflammatory processes occur.
In younger children, we see eosinophilic gastroenteritis.
And in older children,
we would add in the potential diagnosis of inflammatory bowel disease.
All of these diseases are where children would have prolonged areas of diarrhea
going on for a long period of time,
and you’d start to drill down into some of these diagnoses in such a patient.
Additionally, you may see children with immunodeficiency.
These children will usually get other infections as well,
things like severe combined immune deficiency or HIV.
Again, adrenaline sufficiently can cause this, as can hyper or hypoparathyroidism.
So, endocrinopathies can also cause chronic diarrhea.
Other problems can cause chronic diarrhea as well.
Rare things like lymphangiectasias in children, toxin exposure,
and rarely congenital bowel disorders.
In older children, you may see constipation causing what appears to be diarrhea,
when in fact, it’s not, it’s just encopresis;
liquid stools squirting around the hard ball of stool
that the child can no longer get out.
Irritable bowel syndrome starts to happen in older children,
and of course, toxins can rarely cause this as well.