QuestionSBA
QuestionChoice
Dehydration results in hypernatremia and an abnormally elevated serum osmolality. Thus, this is incorrect.
10004159
d
Dehydration
QuestionChoice
Similarly to vomiting, diarrhoea can cause hypovolemic hyponatremia. However, the urine sodium is typically <20.
10004160
e
Diarrhoea
QuestionChoice
This patient is hyponatraemic with a low plasma osmolality and a raised urine sodium. SIADH involves the excess release of ADH resulting in increased water reabsorption in the kidneys resulting in a euvolemic (dilutional) hyponatremia as observed in this patient. SIADH is most commonly caused by malignancy, pulmonary conditions or medications.
10004156
a
SIADH
QuestionChoice
This is a rare laboratory abnormality where there is a low measured sodium concentration in the presence of an actual normal serum sodium levels. It will show as hyponatremia with normal plasma osmolality.
10004158
c
Pseudo-hyponatremia
QuestionChoice
Vomiting can cause hyponatremia, however, this would result in urinary sodium levels of <20.
10004157
b
Vomiting
Concept
Chapter
2693
4241
SIADH
Topic
170
Clinical Chemistry
13378
A 35-year-old female presents to her GP complaining of being thirsty all the time.
Blood tests are performed and a urine sample is obtained.


Her results are as follows:


Plasma

||||
|---------------------------|:-------:|--------------------|
|Sodium|118 mmol/L|135 - 145|
|Urea|2.7 mmol/L|2.5 - 7.8|
|Serum Osmolality|250 mOsmol/kg|285 - 295|

Urine

||||
|---------------------------|:-------:|------------------------------|
|Sodium|41 mmol/L|75 - 300|
|Urine Osmolality|810 mOsmol/kg|50 - 1200|


Which of the following is the most likely cause of this presentation?
a