00:01
Welcome.
00:02
In this talk, we're going to
deal with lactose intolerance.
00:06
Mooo...
00:08
So lactose intolerance is a
constellation of symptoms
that are due to a
lactase deficiency.
00:14
Within the small bowel,
you're lacking an enzyme
that's going to be responsible
for breaking down that sugar,
which is found in a
high concentration
within milk and
other dairy products.
00:26
The epidemiology of this.
00:29
So in children,
there's a very low prevalence.
00:31
Most kids do just fine.
00:34
They have adequate
lactase expression,
certainly until they
get to 6 or even
into their teenage
and young adult years.
00:42
In adults, however,
a greater than 70%.
00:45
So almost three quarters of adults
have a primary lactase deficiency.
00:49
Now, they're not going to be
lactose intolerant, necessarily.
00:53
So about less than half will
actually not be able to drink milk,
they just may not be able to
get the maximum benefit out of it,
and may have some
symptoms related to drinking
liquids that have
lactose within them.
01:10
In adults, the lowest
prevalence for lactase deficiency
or lactose intolerance is
in Northern Europeans.
01:16
It's actually much, much
more common in populations
with African, Asian, Hispanic
and Native American heritage.
01:24
The pathophysiology
is pretty straightforward.
01:26
It has to do with an
enzyme deficiency
in breaking down the lactose.
01:31
So in most adults,
as you get older,
you tend to lose that
enzymatic expression.
01:39
There's a genetic
variability and clearly
in Northern
European populations,
you tend to preserve
expression much more commonly.
01:46
In other populations,
you tend to lose it much more commonly,
and it's an age related decrease
in the lactase expression.
01:53
There may be other
secondary causes.
01:55
So not just a primary age
related loss of expression,
but certain infections
or mucosal disease
such as celiac disease,
or chemotherapy
can cause loss of epithelial
enzyme expression,
or even loss of
epithelial surface area,
which can give manifestations
similar to lactase deficiency.
02:18
Let's look at this
on this schematic.
02:21
So you have in
the small intestine,
you have various compounds
that have been ingested,
In this case,
we're talking about lactose
and lactose is actually a
sugar of glucose and galactose.
02:34
It is a dimer that
needs to be degraded
before the individual
sugars can be absorbed.
02:42
Lactase would normally
break them down into galactose
and glucose which can
be independently absorbed.
02:48
But we don't have
transporter proteins for lactose,
the nondegraded sugar that's
why you need to have lactase.
02:57
In that setting,
we're good to go.
02:59
We've absorbed
galactose and glucose,
whom can use that for energy
and for building blocks, etc.
03:05
In the setting where you
don't have any lactase,
now that lactose
doesn't get broken down,
it can't be absorbed,
it's going to have
an osmotic effect,
it's going to suck in water.
03:16
So that will obviously
increase diarrhea,
but also it's going to be
a really great substrate
for bacterial
fermentation more distally.
03:26
So now the bacteria
are gonna go 'yum',
you've given us sugar
that we can degrade.
03:31
And as they degrade
that that fermentation leads
to production of hydrogen
gas and carbon dioxide.
03:38
It also produces methane
or produce lactic acid,
and acetic acid,
and all of those things create
again, an increased
diuresis or absorption of water
because of all the
solutes that are in there.
03:54
And we end up with loose stools,
we have much more gas,
so there's bloating and flatulence,
and with the expansion
due to the gases,
there will be abdominal pain.
04:06
So the clinical presentation.
04:07
Pretty straightforward once you
understand the pathophysiology.
04:11
The poor unfortunate patient
with lactose intolerance,
who is now had a big bolus
of lactose will have diarrhea,
and there will be bulky
frothy and watery stools
due to the fermentation
of that lactose
by bacteria further
down in the bowel.
04:27
You may actually have
with that increased diarrhea,
poor absorption of
all the other nutrients,
so you may
experience weight loss.
04:36
There clearly be
abdominal pain because
the gas will distend
the bowel and it will hurt.
04:41
And there will be
a sense of bloating,
again, associated with the
fermentation and the gas accumulation.
04:48
And when the gas comes out,
flatulence.
04:51
Nausea because dilation
of the bowel does cause you
to feel sick to your stomach
and you may have frank vomiting.
04:58
Making the diagnosis is
usually kind of cause and effect.
05:02
When you have milk,
you have symptoms.
05:05
So it's a clinical diagnosis.
05:06
And we can do however
other formal testing.
05:10
One is a lactose
hydrogen breath test.
05:12
So we will administer lactose.
05:15
And normally, we don't,
our own GI tract
won't make significant
amounts of hydrogen.
05:23
However,
if you have a lactase deficiency,
that lactose bolus will lead
to a lot of hydrogen formation
that can be detected
in the breath.
05:33
So you get absorption
into the vasculature
and then you breathe it out.
05:40
Some clinicians will also
look specifically for methane.
05:43
And because you
may get other forms
of fermentation depending
on the microbiota.
05:49
In some cases,
you may do a small bowel biopsy
to make sure that there
is not celiac disease
or some other entity that's
causing this lactose intolerance.
05:59
Again, just speaking to
the other secondary causes
of lactose deficiency
or lactase deficiency,
are infectious enteritis can
include giardia and other things,
celiac disease,
so gluten sensitive and neuropathy,
inflammatory bowel disease,
and certainly certain drugs
and radiation induced enteritis will do this as well.
06:18
The management.
06:19
Well just get rid of the milk.
06:21
Okay, do lactose restriction.
06:24
We can also substitute
other forms of milk,
so soy milk or other
vegan alternatives.
06:32
You can concurrently
with the ingestion of lactose
have lactase enzyme
preparations that will enzymatically
break down the lactose
before it gets to the point
where the bacteria will
use it for fermentation.
06:46
And clearly, if you're not drinking
or having as many dairy products,
you do need to increase your
consumption of important nutrients
that are present in milk such
as calcium and vitamin D.
06:58
If it's a secondary cause,
if it's celiac disease,
or it's radiation
induced enteritis
or other things of that nature,
you treat that primary disorder.
07:08
With that, we've reached the end
of lactase deficiency
or lactose intolerance.