Adrenal Disease - Cushing's Syndrome

Question 1

What is Cushing’s Disease?

Answer 1

A condition where a pituitary adenoma secretes excessive ACTH.

Question 2

What is Cushing’s Syndrome?

Answer 2

Signs and symptoms that develop after prolonged abnormal elevation of Cortisol.

Question 3

Aetiology of Cushing’s Syndrome (4).

Answer 3

1. Exogenous Steroids (Long-Term High-Dose).
2. Cushing’s Disease.
3. Adrenal Adenoma.
4. Paraneoplastic Syndrome (SCLC).

Question 4

What is Pseudo-Cushing’s?

Answer 4

Mimic of Cushing’s, often due to alcohol excess or severe depression. Differentiate using Insulin Stress Test.

Question 5

Clinical Features of Cushing’s Syndrome - Appearance (5).

Answer 5

1. Round Moon Face.
2. Central Obesity.
3. Abdominal Striae.
4. Buffalo Hump (Fat Pad on Upper Back).
5. Proximal Limb Muscle Wasting.

Question 6

Clinical Features of Cushing’s Syndrome - Pathology (6).

Answer 6

1. Hypertension.
2. Cardiac Hypertrophy.
3. Type II Diabetes Mellitus (Impaired Glucose Tolerance).
4. Depression.
5. Insomnia.
6. Hypokalaemic Metabolic Alkalosis.

Question 7

Clinical Features of Cushing’s Syndrome (2).

Answer 7

1. Osteoporosis.

2. Easy Bruising and Poor Skin Healing.

Question 8

Investigations in Cushing’s Syndrome (6).

Answer 8

1. Test of Choice : Dexamethasone Suppression Test.
2. 24 Hour Urinary Free Cortisol (Can’t Find Cause).
3. Bloods - (Raised WCC + Low K+).
4. MRI - Pituitary Adenoma.
5. Chest CT - Small Cell Lung Cancer.
6. Abdominal CT - Adrenal Tumours.

Question 9

Dexamethasone Suppression Test Algorithm.

Answer 9

1. Low-Dose 1mg Test : Positive.

2. High-Dose 8mg Test : Elucidate Underlying Cause.

Question 10

Method of Dexamethasone Suppression Test.

Answer 10

1. Dose of Dexamethasone at 10PM.
2. Measure Cortisol and ACTH at 9AM.
3. Aim : Check if Dexamethasone suppresses normal morning spike of Cortisol.

Question 11

Rationale of Low-Dose Suppression Test.

Answer 11

Dexamethasone suppresses release of CRH, ACTH and consequently Cortisol - negative feedback.

Question 12

Results of High-Dose Dexamethasone Suppression Test.

Answer 12

1. Cushing’s Disease -suppresses Cortisol and ACTH.
2. Adrenal Adenoma - suppresses ACTH and not Cortisol.
3. Ectopic ACTH - does not suppress either Cortisol or ACTH.

Question 13

Management of Cushing’s Disease.

Answer 13

Pituitary Tumour Resection.

Question 14

Medical Management of Cushing’s Syndrome (4).

Answer 14

1. Metyrapone - block steroid synthesis.
2. Mifepristone - glucocorticoid antagonist.
3. Ketoconazole - adsrenolytic agent.
4. Pasireotide - binds to Somatostatin receptors.