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So I have a slip of paper. Let's go through these lab values.
I actually put down a number of values that we're going to pretend for a moment are my labs.
And you can see the range and the units next to them.
So let's go through it piece by piece, and actually while I do it I'm actually going to
show you some short hand techniques so you can understand, if you ever see this in the future, what it refers to.
So some short hand that people have come up with, this isn't necessarily something I've come up with.
I learned it from folks ahead of me, but it's been used, not just in the U.S., but most parts of the world.
It's pretty uniform.
So if you're looking at these labs, here's a quick way to transcribe them. So imagine you
have to quickly put it on a piece of paper and move on. This is how you would do it.
So you draw a little stick diagram like that and in the far left you'd put the number "5."
And this refers to the first row, the white blood cell row. And we know the value is 5000 so
that's what the 5 represents. And it's understood that that number is in thousands of cells per milliliter.
So if you see a 5, you know we're talking about thousands of cells per milliliter.
And the next question is well, what are those types of cells if you were to actually look at them? We know they're
white blood cells, but exactly what type they are is actually in the six rows beneath.
So these six rows tell you the breakdown of this number.
So that's why they're percents. And so the 5000 cells break down into:
Segmented neutrophils (I'm gonna write that as an S with a 61).
And Bands, there are 3% bands.
Lymphocytes are 29%, and then we have monocytes at 4%, basophils at 1%, and Eosinophils at 2%.
So these percentages for the different types of white blood cells are going to add up to 100. Right?
So let's just double check. We've got 7 and 29 is 36 and 3 is 39. Yep 100%.
So that's how you quickly can see the different types of white blood cells floating around in your body.
That's what those numbers represent.
So then the next two numbers: hemoglobin and hematocrit go in the top and bottom of this stick diagram.
And again when you see these numbers like this I could look at that and immediately figure out that's the red blood cell content.
Those two numbers both reflect red blood cell content in the blood.
And then the last cell, on this side, represents the platelet count.
And 227 represents 227 thousand cells per microliter. So before we were talking about milliliters (for the white blood cells)
but now for the platelets we're talking about microliters. And in fact I'll put cells in quotes because we know it's
not really cells, it's these are little cell fragments that are the platelets.
So that 227,000 tells you about how many platelet cell fragments are floating around in one microliter of blood.
So that's the first chunk of data. So that's all of this information kind of summarized
very quickly in that stick diagram.
Now let's move on to the chemistries.
So if someone orders a chem 7, then that'd be the first seven of these. And if they order a chem 10
then that would be all ten of these.
So this is how you would kind of draw this out as a stick diagram. It kind of goes like this.
And the chem 10, the last three go in here.
So the Sodium goes in the top left, and below that is the 4.3 for Postassium.
And you're just going systematically all the way through it. So for Chloride it's 103, and bicarbonate goes, it's 22, right below that,
and the Creatinine goes in this cell, 0.8, and the blood urea nitrogen, sometimes they call that the BUN,
that's just the first letter of these three- is 15. And then the fasting glucose is 92.
And then the Calcium goes in the top of this little wishbone shaped stick diagram. That goes right there.
The Magnesium goes on this side, and the Phosphate goes on this side. So that's the Chem 7 on top,
and the Chem 10 would be all of that kind of together.
And then the bottom we have some liver enzymes, and also there's a stick diagram for that as well, kind of a fast way to draw it.
And it is basically just an X. So the top of the X is two numbers, so you usually write the total bilirubin like this
1.1 and then you put a slash and you put the other number there, the direct bilirubin, 0.1.
And then on the left you put the AST and on the right you put the ALT, and at the bottom you
put the Alkaline phosphatase, 76. This is how the numbers kind of break down, so again if you ever see any of these stick
diagrams and you're wondering what they refer to. Now you kind of have broken the code, you know what number goes where.
So if you see, for example, this number, the 22, you immediately know that they're talking about the ALT.
So this is the way that people quickly diagram things. And now I know when people look at labs, the first thing they
want to know is-hey is this good or bad? So they want to look at these values and they want to compare them to the ranges.
They want to say- hey does this fit into the normal range that people expect?
So let's talk about that. Let's talk about normal range, and what normal means exactly because I know that's the first thing
most people will want to look at. So let me draw out what a normal curve would look like. So if you actually took
everybody, let's say 10,000- but it's not everybody, but it's a big chunk of people- 10,000 people and asked them
all to tell you their white blood cell count they will give you, of course, many different numbers.
They're probably wondering what you're doing with that information. But let's say they give you their answer.
And say you plot it all on a curve and you draw a little diagram. This would be basically what you would find.
You'd say- okay most people have a white blood cell- and this is white blood cell count down here- and this is of course in thousands, we said.
Thousands of cells per mililiter. And this is frequency, this is the number of people. I'll just write "f" for frequency.
So you'd say- okay while there are a lot of people kind of in this range right here, and in fact 95% of people fall into this middle section
In this area, so this is definitely the bulk of people that fit between 4.5 and 10.
And that's actually how most of these ranges are decided upon. They say okay where do the bulk of folks lie.
And it's usually between those numbers that are in the range and that also means, if you think about it,
that there's of course somebody out here, and somebody up here. I mean that is by definition going to happen.
You are going to have 5% of people in one of those two tails combined. So whenever you see a range, just keep in mind, there is some
normal variance, they're called, that kind of go above or below that range. But that range usually captures the majority of folks.
So when thinking about that, when thinking about what exactly goes into a normal range. Consider some of
the things that could make what is "normal" different. So for example let's say I may check someone's hematocrit.
Let's say I'm looking at the hematocrit and I want to find out if it's normal or not. If I look at a baby's hematocrit but I use an adult's range
then it would be very very unusually high. So a newborn baby has a very high hematocrit.
So I really should be comparing it to other newborn babies.
So age is really important to consider. So you want to make sure that the range of values is age appropriate.
You also want to make sure that gender is considered. So for example the normal range for men's hematocrit
is a little bit higher than the normal range for women's hematocrit. So range matters for age and also for gender.
Now different labs will also differ. So it's actually quite interesting, you can even go online and see what the normal ranges
for a lot of these things that I have here, and the numbers will be a little different from what I have shown you.
So if you go from one lab to another, you'll get different numbers. And in fact lab technique also matters. So even within
a lab, depending on the technique they use to get an answer to something, the range could differ. And that actually matters
particularly for things like this. So these IUs that I put down here, they stand for International Units.
And that's specific to a type of lab assay that's done and again that depends on the exact assay that's done and that's
going to change the range of values that you get there. So consider the technique.
And finally consider the situation. So if you have, let's say a person who is
supposed to come in for a fasting glucose and usually you're told, you know don't eat anything overnight and
don't have breakfast and come in and get your blood taken first thing in the morning. It's a pretty common scenario.
Then you would have a normal fasting glucose, and it should be below 100. But let's say by accident you
decide to have a little snack in the morning because that's your usual thing, you have some toast.
Umm, your blood glucose could go up as a result. So that glucose result could be okay if someone knows that you didn't fast really,
you had a little snack. So that situation changed, so you're metabolism is going to make that range go up.
So only for fasting glucose is the number below 100 normal. Otherwise it could be higher.
Now consider a situation where you're taking a medication. Let's say you're on a medication that makes your potassium go down.
So you're on a drug that causes potassium to leave your kidneys and go into your urine. Your potassium value would
then go down. I would expect it to be lower right? Because you're taking your medication. So some of these ranges
are going to change depending on what medications you take, what you had for breakfast that day, or not had for breakfast,
what kind of medical conditions you have. So it's going to definitely depend on the situation.
So whenever you look at ranges and values and you want to see if you're in the normal range, just consider all of these things
that could explain why your number may or may not be within that range.