BOF: 114
A 56-year-old female presents with a history of
increasing tiredness. On examination there is pigmentation of her skin creases
and buccal mucosa. Her blood pressure is 90/50.
Investigations are as follows:
Blood urea 8.4 mmol/l
Na 130 mmol/l
Potassium 6.1 mmol/l
Chloride 96 mmol/l
Bicarbonate 23 mmol/l
Which of the following tests will confirm the diagnosis?
a)
Random cortisol measurement
b)
Short ACTH stimulation test
c)
Long ACTH stimulation test
d)
0900 Plasma ACTH level and cortisol measurement
e)
Abdominal x-ray
Answer:
d)
This patient has Addison’s disease. A high 0900 h
plasma ACTH level with low or normal cortisol will confirm the diagnosis of
primary hypoadrenalism
The short ACTH (synacthen) test would show that the
adrenal gland is not responding to ACTH. This may be due to primary
hypoadrenalism or secondary to adrenal suppression by steroids or ACTH
deficiency. Hence it will not confirm the diagnosis. She does not have adrenal
suppression by steroids or ACTH deficiency as her skin creases and buccal
mucosa are pigmented. Hence, a long ACTH stimulation test is not the answer
Revision Tip
Revise Addison's disease KEYS to
SUCCESS in Medicine page 55-57
