Next, her doctor conducted a carefully monitored water deprivation test. The mor
ID: 3479033 • Letter: N
Question
Next, her doctor conducted a carefully monitored water deprivation test. The morning of the test Jamie was weighed at the doctor’s office. Her weight was recorded as 122 lbs. Jamie was to remain at the doctor’s office for the duration of the test. She was put on fluid restriction.A urine and plasma osmolality chart was started. Hourly, the weight of the patient, and her urine and plasma osmolality were measured, and recorded on the chart.
Nurses were instructed to terminate fluid restriction if:
Patient’s weight fell by > 5%
Plasma osmolality increased to > 300 mOsm/kg.
If urine osmolality increased by <30 mOsm/kg (in total) over three successive urine samples patient would proceed to DDAVP test
DDAVP test should be terminated if urine osmolality rose to >750 mOsm/kg
Jamie’s results were as follows:
Post Dehydration Osmolality mOsm/Kg
Post DDAVP Osmolality mOsm/kg
Time
Weight
Urine osmolality
Plasma osmolality
Urine
Plasma
8:00
122 lbs
200
287
9:00
121.5 lbs
200
290
10:00
120 lbs
200
298
DDAVP administered
11:00
815
290
Post-dehydration osmolality (mOsm/kg)
Post DDAVP osmolality (mOsm/kg)
Diagnosis
plasma
urine
urine
283-293
> 750
> 750
normal
> 293
< 300
< 300
nephrogenic diabetes insipidus
> 293
< 300
> 750
cranial diabetes insipidus
< 293
300-750
< 750
chronic polydipsia
< 293
300-750
< 750
partial nephrogenic DI or primary polydipsia
> 293
300-750
> 750
partial cranial DI
Write a short synopsis of the tests, the results, your diagnosis. What are your recommendations to Jamie? Develope a treatment plan?
Post Dehydration Osmolality mOsm/Kg
Post DDAVP Osmolality mOsm/kg
Time
Weight
Urine osmolality
Plasma osmolality
Urine
Plasma
8:00
122 lbs
200
287
9:00
121.5 lbs
200
290
10:00
120 lbs
200
298
DDAVP administered
11:00
815
290
Explanation / Answer
There was no termination for fluid restriction because patient has normal lower plasma osmolality than 300mOsm/kg.
DDAVP test must need to terminate after results from 11:00 hours because patient has higher urine osmolality than 750mOsm/kg.
Diagnosis:
Now due to fluid restriction, the plasma osmlatity has decreased from 298 to 290 mOsm/kg. this is normal level.
However, the urine osmolality is much higher than 750 mOsm/kg after DDAVP test, it suggests that patient has partial cranial Diabetes insipidus (DI). It causes by decreased secretion of antidiuretic hormone (ADH); this leads to develop polyuria and polydipsia.
Treatment:
It is partial cranial Diabetes insipidus, which can manage by drinking of water until quenching of the thirst.
It does not require any specific treatment. It is prescribe to drink at least 2.5 liters water daily.
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