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