Hi, my name is Jill Beavers-Kirby and today
we are going to be talking about
some lab values that you are going to find on
your NCLEX exam. We are not going to talk
about every single lab value, just the most
common ones that are on the test.
So the first one is the electrolytes. We are
going to talk about potassium first.
So potassium is the most common intracellular
ion. You find potassium
in every single cell. Normal potassium values
are 3.5 to 5.0 mEq/L.
Why do we need potassium? Well it keeps our
muscles contracting the way
they should, keeps our heart beating the way
it should and it helps with nerve
conduction. So what is hypokalemia? That is any
potassium level that is less than
3.5 mEq/L. What causes hypokalemia?
Well we lose a lot of
electrolytes in our body fluids. So any time
we have vomiting, nausea, diarrhea
or if somebody is undergoing gastric suctioning.
You usually see this when
somebody has had surgery and they are hooked up to
NG tube, which is the nasogastric
tube, that goes down into their nose.
And sometimes you have the suction of the
extra bile and extra stomach fluids after
surgery to help the patient feel better.
You got to keep in the back your mind
that you are suctioning out the
electrolytes. So what are symptoms of low potassium?
The same symptoms that are
symptoms for pretty much everything else
in medicine, nausea, vomiting and
diarrhea. However with potassium you
may also see an irregular heartbeat.
You can feel this when you check
somebody's radial pulse or
if they're hooked up to a cardiac monitoring,
you might see some little extra beats in there
that don't belong. So how do we treat low potassium?
Well if your patient is able
to eat, you are going to tell them to eat high
potassium foods. What are high potassium
foods? Anything with the peel. So remember P for
potassium, P for peel. So think of potatoes,
they have a peel, bananas those have a peel,
oranges those have a peel. Anything with
the peel has high potassium.
Or if your patient is unable to eat enough
food to keep their potassium level up,
you want to get them potassium supplements.
Unfortunately most potassium
supplements are pretty big pills and patients
don't really like to take them.
But you have to stress the importance of
keeping their potassium levels normal
because of the heart rate and nerve
If your patient is unable to eat and keep
their potassium levels up via foods
or supplements, then you have to give
them IV potassium. You can give that
peripherally through a line in their arms.
In that case you have to give it slow
10 mEq/hr or if they have a central
line they can get
the rates a little faster. But they have to
be on a cardiac monitor to make sure
they are not getting too much potassium too quick.
On the other end of this potassium
balance is high potassium. This is when your
potassium is greater than 5 mEq/L.
We usually see this in kidney failure
remember I said we lose potassium in our body
fluids. So if you are a kidney
failure patient and you are not able to urinate,
your potassium is going to build up.
Another time we see this is when your patient
is taking too many of those
potassium supplements. Those big horse
pills that are hard to swallow.
Sometimes patients really do take them like they
are supposed to and their potassium
levels are too high.
Another thing that causes high potassium
levels are burn or crush injuries.
This comes from the trauma down to the muscle
tissue where potassium is released from
the muscles. It causes your potassium
levels to become elevated. What are
Well you are going to see EKG changes. Those are
tall tented T waves on an EKG. If you
have tall tented T waves on an EKG or on
your heart monitor you want to get an
EKG and assess the patient for a higher level
of potassium. Really high potassium
levels, say around 7 mEq/L
cause muscle weakness, and confusion, and ventricular
fibrillation which will eventually lead
to cardiac arrest. So you have to be very
diligent about monitoring your patient
for elevated levels of potassium. So how
do we fix high potassium?
Well, one of the easiest ways is to tell
the patient quit taking all
the potassium supplements and to stop them
before their potassium levels get too
high. Or there is medicine called Kayexalate
which causes diarrhea. Once again
we are losing our body fluids. So this is
how we get rid of our own potassium.
Kayexalate looks like chocolate milk and
it smells really syrupy sweet.
Patients will usually take it because it is
palatable and it will usually cause
diarrhea in about 30 minutes. So this is
going to help them get rid of their
potassium. Another way to help them get rid of their
potassium is with diuretics
such as Lasix. Why? Because it's causing us to
urinate and we are losing our potassium that
way. If potassium levels are really, really
high you have to put the patient
on dialysis. If it's a kidney patient and
filter out their potassium. You can also
give IV sodium bicarbonate or calcium gluconate.
What this does? Is it forces
the potassium out of the body. The next
electrolyte is sodium. Sodium is the
major extracellular ion. So this is the major
ion that is outside the cells.
Normal is 135 to 145 mEq/L.
And why do we need sodium?
To maintain water balance.
So if you think of sodium as salt, you eat too
much salt, you intake too much sodium, you
get swelling, you get water weight gain, you get
ankle puffiness. All those are
unfortunate side effects that none of us really like.
What do we feel if our sodium
level is too low? If the sodium level is
you'll notice that your patient is confused.
What causes somebody's sodium
levels to go too low?
Those GI losses again, vomiting, gastric suctioning,
too much diuretics.
Some people who have heart failure will take
a lot of diuretics which causes a
lot urination, once again losing all those
body fluids. If you have a
significant burn, the patient lose these through
their skin or if
they have a large wound that is draining
body fluids again.
This can cause low sodium. So your confused little patient is
going to come in and
their mentation is going to be off. They might
have some nausea, they might have
some muscle spasms. When sodium level is getting
really, really low, your patient has a
risk for seizure. So how do we fix low sodium? Well we
encourage sodium rich
foods. I had a patient who loved water chestnuts
wrapped in bacon and he would dip them in soy sauce.
And this helps the sodium. All because those three
foods are themselves high in salt.
You also want to tell them to cut down on
their water because they can dilute out the
blood sodium. Some patients will drink
way too much water and that causes all the
electrolytes to look low. You can
also give sodium via IV which is usually 0.9%
sodium is the normal fluid or if
their sodium is really, really low we give a
hypertonic solution of 0.3% saline.
You have to give this slow and replace
the losses slowly.
Just because the losses didn't occur all of
a sudden. So we replace this losses
gradually over time to allow the body to the equilibrate.
So on the other side is hypernatremia. This
is when your sodium level is greater
than 145 mEq/L. This is usually seen
in dehydration when
patients aren't taking enough water or fluids
or in a metabolic condition
called diabetes insipidus. This is when your
body can't concentrate the fluids.
So even though you have a large amount of
urine output it is not concentrated
at all. So you're hanging onto your sodium.
Or sometimes people just over salt everything
and they just simply taken too much sodium intake.
So what are the symptoms?
Weakness, and confusion, I know sound familiar,
these are the symptoms for
everything. But you can look in their mouth
and their mouth will be really
dry. Their eyes will be really dry. Because
they are dehydrated. Their skin
turgor will be off because once again they are
dehydrated. So you will notice the
tenting of the skin will be longer than
3 seconds. And their blood
pressure might be low because they are dehydrated.
They just don't have enough
fluids going through their system.
So how do we treat this? We treat this with IV
fluids such as dextrose or oral fluids just
as plain water. And we also highly, highly,
highly encourage the patient to quit using
so much salt and salting their
foods. So another electrolyte that's found in our
body is calcium. And on lab
test results, you might see two levels
for calcium. You might see a total
calcium and an
ionized calcium. Ionized calcium is more specific to
the calcium that's in the
specific cells. Total calcium also takes
into account the amount of calcium in
Most physicians will use that ionized
calcium levels to treat patients though.
Why do we need calcium? This is needed
for muscle contraction and blood
clotting. So a normal ionized calcium
is 4.5 to 5.2 mg/dL.
Hypocalcemia is less than 4.5 of an
ionized calcium. What causes this?
pancreatitis which is irritation and inflammation
of your pancreas, diuretics
such as Lasix, steroids such as high
doses of prednisone and
hyperparathyroidism. So your parathyroid
gland is the gland that's
along your thyroid and it also helps to
regulate our calcium. So if your
parathyroid gland is not functioning you can
have an alteration in your level of calcium.
So the symptoms of low calcium are pretty
distinct. One of them is Trousseau's
sign. This is when a patient has a blood pressure
cuff on and as you're inflating
the cuff, the hand will spasm like this
where the middle finger comes into
the palm. It's a pretty classic sign. The other
sign of low calcium is called
Chvostek's. Chovstek's sign is if you tap
the person's cheek, their mouth will
spasm in relation just to the tapping because
you are irritating that nerve.
So how do we treat low calcium? We give them calcium.
You give calcium gluconate or you give calcium
chloride. Calcium will be better absorbed if you can
give it with orange juice. It's kind
of a side note. So if you have low calcium,
then you can also have high calcium.
High calcium is seen when you have certain diseases
such as cancer or with excess
What are the symptoms? Nausea, vomiting,
confusion, and an irregular heartbeat.
High calcemia is harder to pick up on just
because the symptoms are rather vague
and those are the symptoms for pretty much
everything else. But we treat this
by giving the patients IV fluids such as normal
saline to help kind of dilute that
calcium amount, diuretics to help them rid
their body of their body fluids, all that
excess water, oral fluids if they are able to
eat and drink enough to sustain. Or you
can give a binding agent called Calcitonin.
This is an IV medication.
It binds to the extra calcium in the system,
so that the calcium doesn't affect the
other body parts.
Another very important electrolyte is magnesium.
Normal magnesium is 1.5 to 3 mEq/L.
Magnesium is needed for muscle and nerve conduction,
heartbeat, regulation of blood pressure and
blood sugar. So remember magnesium,
muscles when you think muscles, think of
nerves because you have to have nerves
to make your muscles move. So M for
magnesium, M for muscles.
Hypomagnesemia or low magnesium is defined
as a magnesium level of less
than 1.5 mEq/L. This is caused from
absorption. So if you are eating and for
whatever reason your gut just can't
absorb the electrolytes or from diarrhea. Once
again you are getting rid
of body fluids and that's where all your
electrolytes are. Alcoholism, because of
poor nutrition or poorly controlled diabetes.
Because high blood glucose
is not allowing your body to absorb the magnesium.
So what are the symptoms? You are
going to see hyperactive reflexes, remember M
for magnesium, M for muscles and the
nerves innervate your muscles. So your muscles
are going to be very over
reflexic. You can also be confused. You can
also have some tremors. And if the
low magnesium level goes on long enough
it can lead to seizures. So how do we
treat low magnesium?
If the patient is able to eat, we ask him to
increase the intake of
foods that are high in magnesium. This includes
greens like kale, spinach.
It also includes chocolates and nuts. So one
of the best way to replace your
magnesium is to eat chocolate covered nuts.
Dark chocolate has more magnesium
in it. So that is even better for the patient.
You can also supplement
magnesium with intravenous magnesium. You can
give 2gms/hr via an IV even in a
peripheral IV. Another way to supplement
magnesium is with magnesium pills.
However one of the biggest side effects of
magnesium pills is diarrhea. So it is
really hard to tell your patient to take magnesium
pills which may cause diarrhea
which may make you lose your magnesium but take
more pills. So best thing to
do if they are able to eat and drink have them
try to increase their foods
rich in magnesium. Once again that is nuts, green
vegetables, dark chocolate and tofu.
Tofu has lot of magnesium in it.
So if we have low magnesium, we can have
high magnesium. High magnesium, you are not
going to really see a whole lot in your career.
But that is defined as anything greater
than 3 mEq/L. This is usually
in your kidney failure patients who are on
dialysis and once again they don't
urinates, so they don't lose their electrolytes.
So all that has to be done
artificially through hemodialysis. Or people
who like to take a lot of
magnesium rich medications. These are usually
your antacids. So what are
the symptoms of high magnesium? Heart
irregularities, confusion, muscle weakness
and if left get on too long you can have
temporary paralysis. So how do we
treatment high magnesium? Tell the patient
to stop taking so many antacids
and they might need hemodialysis that help to
throw out some of that or we can give IV
calcium gluconate to offset the level of magnesium.
Some other important lab
values you are going to see on your exam are a
complete blood count also known as a CBC.
The important things that you need to
look for on your CBC are red blood cells
which are needed for oxygen transport. Normals
are different from men and for
women. In general women's CBC values are going
to be a little lower.
Because we were made different. We have less
muscle than men and we have a little bit less
blood flow than men.
Another component you are going to see on your
CBC are white blood cells. These are
need to protect you from infection. So a
white blood cell is a total number of
all the things that are making up all the
different types of white blood cells.
So there could be eosinophils, granulocytes,
macrophages. All those are different types of
white blood cells. But the total
WBC count is going to be the total of all those
things that are making that up.
So for the NCLEX you just need to constrain
yourself with the total number
of WBCs. Platelets, those are needed to
help your blood clot. If your platelet count is
too low, you have trouble clotting.
Your platelet count is too high,
this can clog some of your organs especially
your spleen. Hemoglobin is
needed to transport oxygen into the blood. Once
again the numbers are little
different from men and women. Normals are little
bit lower for women. And then your
hematocrit is always listed as a proportion
or percentage. This is the
proportion of blood that consists of
blood cells. Once again
numbers are a little different from men and for
women, usually lower for women.
Another set of lab values that you are going
to see on your NCLEX exam is an
arterial blood gas report also known as ABG.
This is important to tell us how
well we are perfusing oxygen and
carbon dioxide in our blood
and how well our body is maintaining our
pH balance. So the pH tells us if we are
in an acidotic state or an alkalotic state.
Normal blood pH is 7.35 to 7.45.
If it's less than 7.35, it's considered to
be acidotic. If it's greater than
7.45, it's considered to be alkalotic.
Another number that you are going to see on
this ABG report is the normal paO2. This is
the amount of oxygen that is in our
blood. You might see this abbreviated as
pO2 also. The normal paO2 should be 80
to 100% because we want a lot of oxygen in
our blood. This number can be higher than
100% if your patient is on supplement
of oxygen such as a nasal
cannula on a ventilator. Another number on
this blood gas report is the
number of carbon dioxide in our blood.
So normal paCO2 is 35 to
You got to
remember you are blowing out your CO2.
You don't want a lot of CO2 in your body.
If your CO2 level gets too high, you get
confused, you get lethargic, you get
sleepy. So if these numbers are off, something
is wrong with the way your
patient is breathing. They are either
breathing too fast,
blowing off too much CO2 or they are breathing
too slow and maintaining their CO2.
And finally one of the other numbers that
you'll see on this blood
gas report is the bicarbonate of the blood. The
bicarbonate of the blood is what helps us
maintain a normal pH. So normal bicarbonate
blood is 24 to
26 mEq/L. And finally another
test result that you are going to
see on your NCLEX exam are things called
coagulation times. This tells us how well
the blood is clotting. There's three basic
test results that you have to
remember PTT, PT, and your INR.
So the PTT is the partial thromboplastin time.
This is normally about 20 to 36
seconds. We check
PTTs whenever giving somebody an IV heparin
infusion. So if somebody has a blood
clot, they are on an IV heparin drip you have
to monitor their PTT time.
That's how you adjust their heparin.
Another is their prothrombin time.
Normally this is 9 to 12 seconds. PTT is going
to be more accurate when you
administering IV heparin. And finally the
INR. INR simply stands for
International Normalized Ratio. This is
used to monitor warfarin also known
as Coumadin. The level that you want somebody's
INR to be, depends on why
they are getting the Coumadin. So we would
like an INR usually to be
anywhere from 2 to 3 or 2.5 to 3.5. I guess
that is just depend on why
they are on the Coumadin. So if somebody's
INR times are too high, say you
check their INR and its 5, that puts them
at a higher risk for bleeding and in
order to correct that, you give the patient
vitamin K. Vitamin K can either be given
IV or intramuscularly. But when an elevated INR
is the reason you are giving
the vitamin K, you usually give it via an IV. Thank you.
This has been Jill Beavers-Kirby discussing lab values.