So if we see a child
it’s indicated to get a Chem-7,
especially for severe dehydration
because we’re concerned about
imbalance of electrolytes.
And the electrolyte that gets children
in trouble the most is actually sodium.
It is not necessary to get a Chem-7
for a child who has mild dehydration unless
you have other concerns about the child.
Because those children,
once their fluids have been replenished,
will normalize their Chem-7.
So this is how a Chem-7 on
your slide here is organized
when we draw it out shorthand
on a piece of paper.
Sodium, potassium, chloride, bicarb,
BUN and creatinine, and glucose.
Let’s go through some examples.
Here are normal values for your Chem-7.
The sodium is 140, the
potassium is around 3.8.
In this child, the chloride is normal
at 110, and a normal bicarb is 24.
That 24 and that 140 are usually fairly
carefully constricted at that normal value.
The next numbers, the 5 and 0.2,
are the BUN and creatinine.
Those will herald signs of
dehydration if the BUN is very high.
But the creatinine will remain normal
unless the child is in renal failure
or very severely dehydrated.
Glucose may be not so important in
adults, but in children, it’s critical.
Because young children, when they get
dehydrated, often get hypoglycemic.
This is because children’s liver stores
of glycogen are much smaller than adults.
That means that without being
fed for a period of time,
they’re at much more
risk for hypoglycemia
and potentially even seizure from a
prolonged period of dehydration.
So here’s what a mild
dehydration may look like.
You can see our patient’s sodium, potassium,
chloride and bicarb are all doing okay.
The BUN has started coming up a little bit
and you can see the glucose has come
down to 70, starting to drift down.
You might even see a slightly low
19 or 20 wouldn’t be surprising.
But those are the key things
that you’re going to see first.
Here’s a child with
The sodium is
starting to creep up.
In this case, this child
is just not drinking.
If the child were eating, say some liquid,
but losing more liquid
than she were drinking,
that child might have a low sodium
even in the face of dehydration.
You can see that now, the
child’s bicarbonate is low.
It’s significantly acidotic
all the way down to 13.
And the chloride is starting to
creep up as a compensatory method.
But there’s something special
about this that we have to note
and it has to do with the sodium,
the chloride and the bicarb.
Remember your equation
for calculating a gap.
In this case, this child
has large anion gap,
which is a sign that this child is
also having a metabolic acidosis.
I’m guessing this child
either has ketones
or this child has lactic acidosis,
which might be driving that gap.
Again, the BUN is coming up and
now the creatinine is coming up
and look how low that
glucose is getting.
Not surprising at all for a child
with moderate dehydration.
So all these numbers are starting
to become pretty significant
and the anion gap is 20,
145 minus 112 minus 13.
In severe dehydration, now we’re
really getting into trouble.
This child’s sodium
is still high.
It might get much higher and we have to
do some very fancy calculations to fix.
But of note, the
chloride’s coming up.
The bicarb’s coming way down and the BUN
and creatinine are significantly elevated.
Look how hypoglycemic
this child is.
You can see how this will happen