QuestionSBA
QuestionChoice
Central obesity, proximal weakness, depression and abdominal striae are typical of Cushing’s syndrome. The diagnostic investigation for Cushing’s syndrome is a low dose dexamethasone suppression test.

By contrast, 24-hour plasma metanephrines would be a diagnostic investigation if you suspect pheochromocytoma. The classic presentation of pheochromocytoma includes symptoms of episodic hypertension, anxiety, palpations, headaches and signs like tremor and hypertensive retinopathy.
10007609
d
24-hour plasma metanephrines
QuestionChoice
This patient presents with the key symptoms of Cushing’s syndrome: proximal myopathy, striae, obesity, and depression. It can also manifest as osteoporosis, a 'moon' shaped face, diabetes mellitus, hypokalaemia and hypertension. The diagnostic investigation for Cushing’s syndrome is a low dose dexamethasone suppression test.
10007606
a
Dexamethasone suppression test
QuestionChoice
Central obesity, proximal weakness, depression and abdominal striae are typical of Cushing’s syndrome. A fluid deprivation test can be performed to diagnose diabetes insipidus, but would not be diagnostic in this case. The diagnostic investigation for Cushing’s syndrome is a low dose dexamethasone suppression test.

Diabetes insipidus is characterized by patients producing large volumes of dilute urine, nocturia and excessive thirst. Before a fluid deprivation test, some baseline investigations involve renal function tests, blood glucose, urine dip and serum and urine osmolality tests.
10007608
c
Fluid deprivation test
QuestionChoice
Central obesity, proximal weakness, depression and abdominal striae are typical of Cushing’s syndrome. HbA1c is a useful diagnostic test for diabetes mellitus, but would not be diagnostic in this case. The diagnostic investigation for Cushing’s syndrome is a low dose dexamethasone suppression test.
10007607
b
HbA1c
QuestionChoice
Central obesity, proximal weakness, depression and abdominal striae are typical of Cushing’s syndrome. The diagnostic investigation for Cushing’s syndrome is a low dose dexamethasone suppression test.

By contrast, a short synacthen test would confirm the diagnosis of Adrenal sufficiency, not Cushing’s disease. Adrenal insufficiency would present with symptoms like hypotension, fatigue and weakness, gastrointestinal symptoms, syncope and skin pigmentation. Blood tests would also show low sodium and high potassium.
10007610
e
Short synacthen test
Concept
Chapter
2693
3764
Cushing's syndrome
Topic
133
Endocrinology
14068
A 25-year-old male attends the GP surgery after noticing a large amount of weight gain, particularly around his abdomen. He has also felt low in mood recently.

On examination, you observe abdominal striae and weakness in all four of his proximal limbs.

Which of the following is the next best investigation?
a