00:01
Let's go on to another case.
00:03
An otherwise healthy
28-year old woman
who is eight months postpartum
comes to see you
because she has excessive
thirst and urination.
00:11
She still has amenorrhea
since giving birth.
00:15
Her vital signs are normal
and physical exam is normal
other than
dry mucous membranes.
00:21
The serum glucose is
90 milligrams per deciliter, sodium 146,
calcium 8.1, and measured urine output
4 liters per day.
00:30
What is the most
likely diagnosis?
Here, we have
a postpartum patient.
00:38
She has secondary amenorrhea
in addition to
excessive thirst and
excessive urination.
00:44
This is manifesting with
evidence of dehydration.
00:48
She also has
elevated urine output.
00:51
Clinically, she most likely has
central diabetes insipidus,
and you need to check a simultaneous
urine and serum osmolarity.
01:00
Excretion of more than three liters
of urine per day is defined as polyuria.
01:05
Diagnosis should be made
clearly using the above information.
01:09
However, a water deprivation test may be
beneficial if the diagnosis is unclear.
01:15
In this patient, she has
a normal sodium level.
01:19
If the sodium is on
the higher side,
always use caution when doing
a water deprivation test
as the patient's serum sodium
may rise extremely high
and cause clinical symptoms.
01:33
The main thing driving the normal sodium
in this particular patient’s case
is that with her central diabetes insipidus
and her increased thirst,
she's able to take in
enough fluid
to be able to maintain
a normal serum sodium level.
01:50
Serum osmolarity greater than
295 milliosmols per kilogram
with an inappropriately
dilute urine
will give you
the confirmation of the diagnosis
or low urine osmolarity or urine to serum
osmolarity ratio of less than two.