Endocrinology and metabolic for AMC MCQ

A 42 year old woman has gained weight centrally with a rounded face and a fat pad at the back of her neck, purple abdominal striae, easy bruising and weakness climbing stairs. She has new hypertension and a raised glucose. She takes no regular medication. An overnight dexamethasone suppression test fails to suppress her cortisol. What is the most likely diagnosis?

1. Depression A pseudo-Cushing state with cortisol changes. Central obesity, striae and proximal myopathy with failed cortisol suppression argues for confirmatory testing.
2. Cushing syndrome correct Correct. Central obesity, striae, proximal myopathy, hypertension and glucose intolerance with failed cortisol suppression is Cushing syndrome.
3. Type 2 diabetes with obesity Glucose intolerance without the specific Cushingoid features. Central obesity, striae and proximal myopathy with failed cortisol suppression points elsewhere.
4. Exogenous steroid use The commonest cause, from prescribed glucocorticoids. Central obesity, striae and proximal myopathy with failed cortisol suppression makes the drug history matter.
5. Alcohol excess A pseudo-Cushing picture from alcohol. Central obesity, striae and proximal myopathy with failed cortisol suppression suggests it.

The point: Cushing syndrome is the effect of chronic cortisol excess. By far the commonest cause overall is exogenous, from prescribed glucocorticoids, so a drug history comes first. Endogenous causes divide by ACTH: an ACTH-secreting pituitary adenoma is Cushing disease, the commonest endogenous cause, while an adrenal tumour or an ectopic ACTH source, often a small cell lung cancer, are the others. The features are central obesity with a moon face and buffalo hump, purple striae, easy bruising, proximal myopathy, hypertension, glucose intolerance and osteoporosis. Confirm cortisol excess first with an overnight dexamethasone suppression test, 24-hour urinary free cortisol or late-night salivary cortisol, and only then measure ACTH to localise the source, with imaging. Management is to withdraw exogenous steroids where possible, or surgery for a tumour. Do not stop long-term therapeutic steroids abruptly, because the suppressed axis will not respond and an adrenal crisis follows.

Source: Therapeutic Guidelines (Australia) — Endocrinology: Cushing syndrome Therapeutic Guidelines (Australia) · tier 3, national formulary

A 42 year old woman has gained weight centrally with a rounded face and a fat pad at the back of her neck, purple abdominal striae, easy bruising and weakness climbing stairs. She has new hypertension and a raised glucose. She takes no regular medication. An overnight dexamethasone suppression test fails to suppress her cortisol. What is the most appropriate initial investigation?

1. Overnight dexamethasone suppression test correct Correct. The failure to suppress cortisol confirms endogenous cortisol excess.
2. Pituitary and adrenal imaging Localises the tumour once biochemistry directs it. Central obesity, striae and proximal myopathy with failed cortisol suppression indicates it.
3. Screening for complications Blood pressure, glucose and bone density. Central obesity, striae and proximal myopathy with failed cortisol suppression makes it necessary.
4. ACTH level to localise the source After confirming excess, ACTH is measured to localise the source between pituitary, adrenal and ectopic causes, and central obesity, striae and proximal myopathy with failed cortisol suppression here points elsewhere.
5. Assessment for an ectopic source A small cell lung cancer where ACTH is high. Central obesity, striae and proximal myopathy with failed cortisol suppression makes it worthwhile.

The point: Cushing syndrome is the effect of chronic cortisol excess. By far the commonest cause overall is exogenous, from prescribed glucocorticoids, so a drug history comes first. Endogenous causes divide by ACTH: an ACTH-secreting pituitary adenoma is Cushing disease, the commonest endogenous cause, while an adrenal tumour or an ectopic ACTH source, often a small cell lung cancer, are the others. The features are central obesity with a moon face and buffalo hump, purple striae, easy bruising, proximal myopathy, hypertension, glucose intolerance and osteoporosis. Confirm cortisol excess first with an overnight dexamethasone suppression test, 24-hour urinary free cortisol or late-night salivary cortisol, and only then measure ACTH to localise the source, with imaging. Management is to withdraw exogenous steroids where possible, or surgery for a tumour. Do not stop long-term therapeutic steroids abruptly, because the suppressed axis will not respond and an adrenal crisis follows.

Source: Therapeutic Guidelines (Australia) — Endocrinology: Cushing syndrome Therapeutic Guidelines (Australia) · tier 3, national formulary

A 42 year old woman has gained weight centrally with a rounded face and a fat pad at the back of her neck, purple abdominal striae, easy bruising and weakness climbing stairs. She has new hypertension and a raised glucose. She takes no regular medication. An overnight dexamethasone suppression test fails to suppress her cortisol. What is the most appropriate next step in management?

1. Withdraw exogenous steroids where possible For the commonest cause, tapered not stopped abruptly. Central obesity, striae and proximal myopathy with failed cortisol suppression makes it central.
2. Endocrinology referral For diagnosis and management. Central obesity, striae and proximal myopathy with failed cortisol suppression makes it comprehensive.
3. Manage hypertension, diabetes and osteoporosis The complications of cortisol excess. Central obesity, striae and proximal myopathy with failed cortisol suppression makes it supportive.
4. Treat an ectopic ACTH source Where a tumour is producing ACTH. Central obesity, striae and proximal myopathy with failed cortisol suppression redirects it.
5. Transsphenoidal surgery for a pituitary adenoma correct Correct. If ACTH localises the source to a pituitary adenoma, transsphenoidal surgery is the treatment for Cushing disease.

The point: Cushing syndrome is the effect of chronic cortisol excess. By far the commonest cause overall is exogenous, from prescribed glucocorticoids, so a drug history comes first. Endogenous causes divide by ACTH: an ACTH-secreting pituitary adenoma is Cushing disease, the commonest endogenous cause, while an adrenal tumour or an ectopic ACTH source, often a small cell lung cancer, are the others. The features are central obesity with a moon face and buffalo hump, purple striae, easy bruising, proximal myopathy, hypertension, glucose intolerance and osteoporosis. Confirm cortisol excess first with an overnight dexamethasone suppression test, 24-hour urinary free cortisol or late-night salivary cortisol, and only then measure ACTH to localise the source, with imaging. Management is to withdraw exogenous steroids where possible, or surgery for a tumour. Do not stop long-term therapeutic steroids abruptly, because the suppressed axis will not respond and an adrenal crisis follows.

Source: Therapeutic Guidelines (Australia) — Endocrinology: Cushing syndrome Therapeutic Guidelines (Australia) · tier 3, national formulary