Urinalysis Interpretation Explained Clearly – Glucose & Ketones in Urine
22
August

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , , /


okay well welcome to another MedCram
lecture we’re going to talk about your analysis again and this time we’re gonna
go into with the urinalysis of glucose ketones bilirubin urobilinogen and
specific gravity with respect to the urine okay let’s get started with
glucose we use a peroxide method which will become important later so we use
peroxides to measure glucose a peroxide reaction and the thing that you should
know that’s important is that when blood goes to the nephron there is a barrier
there in the nephron that is preventing glucose from being spilled into Bowman’s
capsule and the proximal convoluted tubule
so if you can kind of imagine a dam with a wall and there is water so long as the
water doesn’t go over that damn wall there won’t be spillage over it that’s
the same analogy that we use with glucose and the number that you should
know for glucose is called the TM which stands for the transport maximum and in
this case that number is 180 micrograms per deciliter which means that if the
glucose concentration is greater than 180 milligrams per deciliter then there
could be spillage of glucose into the urine but if it is less than 180
milligrams per deciliter there should not be now if you do get that you’re
gonna have glucose that’s gonna be found in the urine and that has the effect of
drawing in fluid because of its osmotic principle and you’re gonna get an
osmotic diuresis but we’ll talk about that so again remember peroxidase and
also 180 milligrams per deciliter okay so what you’re gonna see on a test on a
urine test it’s either good to be negative or it’s going to be positive
and degrees of positivity as we talked about before there is a way to make this
thing a false negative and so you have to be careful that if the patient is
taking high levels of vitamin C that can may
glucose even though there is glucose in the urine it could make it look negative
so there are things that can metabolize the vitamin C’s so you don’t get those
false negatives just so you’re aware in terms of positive you could have a trace
you can have a 1 plus a 2 plus a 3 plus and a 4 plus and these generally are
associated with approximately 100 milligrams per deciliter 250 500 a
thousand and up to 2,000 milligrams per deciliter in the urine okay so you could
get quite a bit of spillage of glucose in the urine okay so what does this mean
you see a positive glucose going on what does that mean there’s two possibilities
using our analogy either you’ve got a bad wall okay that means that the damn
wall is not holding back the water and it’s leaking out or you’ve got spillover
okay so the bad wall is much more rare and
the spillover is much more common so let’s talk about the bad wall first this
is sometimes known as fan Kony’s syndrome with Vanko knee syndrome you
have a problem with reabsorption at the proximal convoluted tubules so you also
see dumping of phosphate you’ll also see dumping of uric acid you’ll also see
dumping of bicarbonate now if you remember if you don’t reabsorb
bicarbonate well at the proximal convoluted tubule this is known as a
renal tubular acidosis type 2 okay and that gets into the pH and then of course
the other thing that you see that gets dumped our amino acids now what are
things that can cause this Vanko knee syndrome well it could have something
called multiple myeloma that is a cancerous disease where you have plasma
cells that’s overpopulate all the things that could do this would be heavy metals
other things that could do this would be medications for instance 10 of there
which is an HIV medication chemo therapeutic agents like
cisplatin can do it another medication that’s used in mood disturbances that’s
vpa or valproic acid and then antibiotic which is used commonly is
aminoglycosides so that would be like gentamicin tobramycin amikacin so immuno
clyde’s can do this so all of these causes can cause the Fanconi syndrome
where we have a bad wall so in terms of spillover though where the wall is fine
but you just have too much glucose in the blood the biggest one there you got
to know about is diabetes and of course you can have type 1 you can have type 2
you could have even gestational diabetes that could do it and anything basically
that will increase your blood glucose for instance Cushing’s disease that
could do it and that list goes pretty deep so those are the causes of glucose
in the urine okay let’s change up the color a little bit let’s talk about
ketones so ketones in the urine it’s not usually as useful as serum ketones now
that those are more available so this is kind of an older test the way that those
are checked for is something that you should know called the Nitro pro side
test so what are the major reasons why somebody would have ketones in their
urine one of them is alcohol so alcoholic ketosis another one would be
of course DKA which is diabetic ketoacidosis and then finally the last
one would be starvation ketoacidosis so what are ketones specifically well the
thing that you’ve got to remember is in the cell you’ve got the nucleus of
course but you’ve got these mitochondria all throughout and in the mitochondria
inside them specifically are where fatty acids get transported into the matrix of
the mitochondria where something called beta oxidation occurs and beta oxidation
takes fatty acids and transforms them into acetic away
which are two carbon units so these two carbon units if there’s a lot of this
fatty acid transformation into two carbon units a lot of acids filled Kawai
becomes available and normally that acetic away as you already know should
go into the krebs cycle but if there’s too much of it around and the krebs
cycle can’t handle it then they start to coalesce with each other and so if you
have this a steel Kawai which looks somewhat like this and you bind these
together you’re going to get things like acetoacetate and beta-hydroxybutyrate and acetone if you have two of these
you’re going to make one acetoacetate and what does the COS state look like it
looks like this there’s one two three four carbons
now acetoacetate can be converted and goes back and forth to
beta-hydroxybutyrate to look like this and as you can see here we have a
carbonyl group being reduced to a hydroxy group and so because this is
being reduced something has to be oxidized and that’s where you take and a
D H and you oxidize it to n a D+ so you can get beta-hydroxybutyrate you can get
acetoacetate of course what you can do is you could simply just chop off the
co2 and then what you would get then is simply acetone which you breathe off so
when you do the nitroprusside test that checks for specifically acetoacetate and
the way it does that is through this nitroprusside reaction which involves
nitro for a cyanide which turns it a nice purplish blue and that’s why we’re
kind of writing it in blue here and what would you get
so with ketones you’re either going to get a negative or a positive and if you
get a negative or positive you’re gonna get this purple color
that’s going to turn the ketones positive but there’s also different
levels of positive there’s trace there’s 1 + 2 + 3 + + 4 + and so for trace that
works out to be about 5 milligrams per deciliter 1 + is 15 2 + is 43 + is 80 +
4 + finally is about 160 or more thing here that you should know is that if
ketones are positive you really should be checking them in the serum


9 thoughts on “Urinalysis Interpretation Explained Clearly – Glucose & Ketones in Urine

  1. Yet most of our urine kits is designed to discover the acetoacetate and neglect the beta hydroxybutarate which is why we might have a DKA or alcholic KA pts. negative for keton

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