00:02
Let’s talk about dysregulation of ADH.
00:05
ADH dysfunction, either deficiency central
diabetes insipidus or receptor dysfunction
for ADH.
00:17
Nephrogenic diabetes insipidus is going to
release… is going to result in what type
of urine?
Good, diluted urine.
00:26
What’s your urine osmolality in these patients?
Always decreased.
00:31
What’s your plasma osmolality in these patients?
Always increased.
00:38
Who are my patients?
Central or nephrogenic diabetes insipidus.
00:44
In either case, you’ll have ADH dysfunction,
it’s not working properly.
00:51
Inability to concentrate the urine, what kind
of urine again?
The diluted urine.
00:58
This patient is going to have polyuria, increased
frequency.
01:02
Right off the bag, this gives you a differential
known as diabetes mellitus.
01:05
How can you tell the difference?
In diabetes insipidus, you wouldn’t have
any hypoglycemia, your glucose cell were perfectly
normal.
01:14
However, polyuria is definitely present and
polydipsia.
01:18
Now, in psychogenic polydipsia... psychogenic
polydipsia, what’s that mean to you?
Have you heard of primary polydipsia?
Psychogenic, meaning to say that the patient
might be of schizophrenic type and therefore,
may feel the need to be drinking water all
the time.
01:38
Why am I bringing that up?
Because if you are drinking water all the
time, let’s just say right now, you just
take an entire litre of water and you just
start guzzling it.
01:48
This is a patient or you or me, it doesn’t
matter, we’re going to produce diluted urine.
01:53
What kind of urine do you have in diabetes
insipidus?
Diluted urine.
01:56
So, what’s the difference?
Take a look at the note.
01:59
The note is, if your patient has primary polydipsia,
psychogenic polydipsia, you’re drinking
all that water as oppose to diabetes insipidus
when you’re drinking water by itself, your
plasma osmolality will be low.
02:14
I began this section by asking you what’s
my plasma osmolality in a patient with diabetes
insipidus?
Always high.
02:22
Is that clear?
So, what’s your next step of management
here?
Do not give drugs, it’s a water deprivation
test.
02:30
But, what if your patient was schizophrenic?
It doesn’t matter, it’s water deprivation,
you will contain your patient and deprive
your patient of water.
02:40
Now, not eternally, of course, but to see
as to what then happens to your changes within
the urine and plasma osmolality.
02:47
Now, diuresis results in dehydration.
02:53
When there’s dehydration, there will be
relative hypernatremia and if the patient
is unable to maintain adequate water intake,
impaired thirst mechanism or lack of access
to water are two things that you’re thinking
of.
03:08
So, here, we have two more differentials,
but this is in reference to the plasma osmolality.
03:16
Pay attention to this bullet point.
03:18
Plasma osmolality is increased in diabetes
insipidus either central or nephrogenic, it
does not matter.
03:27
If your patient does not have access to water
because, oh my goodness, they’ve been dropped
in the middle of the desert, haha, their plasma
osmolality will be elevated as well.
03:38
How can you tell the difference?
Oh, urine osmolality.
03:44
Urine osmolality in a patient who doesn’t
have access to water is going to be increased,
it’s concentrated urine.
03:52
In diabetes insipidus, what is urine osmolality
always?
Decreased, decreased, decreased.