Hi, welcome to our video series on interpreting lab values. In this portion, we're going to look
at a urinalysis microscopic exam and look at the 7 key findings of a microscopic exam. So,
what is a microscopic urinalysis? Remember it's one of the 3 parts of a complete urinalysis.
You have a physical exam. You look at it. You have a chemical exam, you break down the
properties of it, and then we do a microscopic exam if it's indicated. So a lab professional will
view a sample of the urine sediment. Okay, underline the word sediment because that's
important. It's more concentrated. So a lab professional takes a look at a sample of the urine
sediment under a microscope to look for things like casts, cells, crystals, and bacteria. Okay,
so when a healthcare team member uses these results, they take patient assessment
information, the results of the urinalysis, and they can diagnose and monitor a wide variety
of conditions. So this is a pretty important test. So let's pause here for just a minute and
talk about urine sediment. You'll see on the left side of your picture, you'll see a little tube
that represents a sample that's 10 to 15 mL. Now, that is not very much, right. It takes 30 mL
to make an ounce, so we're talking about a half an ounce or just a little bit less than that.
You put it in the tube. You spin it around at 3,000 rotations per minute. That's pretty fast.
Do that for 5 minutes and here's what happens. You have the sediment will sink to the
bottom and the fluid will rise to the top. So the lab professional will pour off the excess fluid
from the top of the sample. Then, you'll gently shake that to re-suspend it. So you take that
sample that we've spun around, pour off the excess fluid, and then you gently shake what's
remaining to re-suspend that sediment. Then you take a drop of that, remove it from the
tube, and examine it under the magnification of a microscope. So, what does a microscope see
that we can't? Well, we're going to look at 7 specific things, but the first one of the seven is
RBCs or red blood cells. Now, this could be benign, meaning not really that big a problem or it
could reflect a really serious underlying disease. So, the first one of seven are red blood cells.
Those results can indicate anything from "Ah, not that big a deal to "Oh my goodness, we've
got a real problem. The second one white blood cells or you'll see that abbreviated as WBC.
The third one is a com you're probably not as familiar with, renal tubular epithelial cells,
transitional epithelial cells, and squamous epithelial cells. Now, this could be a contamination
by genital secretions. It might be renal tubular cells, transitional cells, squamous cells. We're
going to dig deeper into that as we go through the rest of this video series. So we've got the
first 3 things, right. We've talked about red blood cells, white blood cells, and epithelial cells.
Now we know that squamous epithelial cells are coming from the outside. We're not so
interested on those, that's a contaminated one. But the other ones, renal tubular and
transitional epithelial, those get our attention. So there's the first 3. Let's look at the
final 4 of the 7 key things, bacteria or fungi. The bacteria is good in a healthy gut but I don't
want to see it in my urinary tract. So if you see bacteria or fungi on a microscopic exam,
we're going to need to follow up. Number 5, crystals. So, this could be uric acid crystals,
calcium phosphate, calcium oxalate crystals, cystine, blah, blah, blah. I know you've stopped
listening to me by now, but if you're someone who's ever had kidney stones, you know that
often they're made of calcium oxalate. Kidney stones, we can see. They're big enough to be
painful and I could see them with a naked eye, but these crystals can be so small, same type
of content, but they need to be viewed under a microscope. Number 6, lipid droplets. Now,
these are commonly seen in a urinalysis on patients who have nephrotic syndrome. So, never
a good sign to see those. And finally number 7 are casts. Now, casts are kind of a mold. The
material solidifies or gets really thick and stiff inside the lumen of the kidney tubules. Think
back to what we know about how the kidney functions. The blood is delivered to the kidney.
You've got the Bowman's capsule with that tangle of capillaries inside, that's the glomerulus.
Now remember that leads into the tubules. They're shaped like a tube that's why they're
called that, in the tubules where things are reabsorbed, but you end up with these casts or
molds of that same shape. They're made of a material of protein right in the lumen or the
opening of that tube, now more specifically right in the nephron, and once they're formed,
these molds or casts of the tubule are eliminated, you guessed it, out through the urine and
can be seen or visible in the urine sediment underneath a microscope.