Cushing's Flashcards
What are some key features of Cushing’s?
Truncal Obesity Increased Deposition of Fat: face, clavicles, back of neck, abdomen Decreased Deposition of Fat: extremities
Violaceous Stretch Marks
Easy Bruising
What are some signs and symptoms of Cushing’s?
Truncal obesity 97% Moon face 89% Hypertension 76% Skin atrophy and bruising 75% Diabetes or glucose intolerance 70% Gonadal dysfunction 69% Muscle weakness 68% Hirsutism, acne
What are the causes of glucocorticoid excess?
Iatrogenic - most common (exogenous steroids)
Pituitary Tumor (Cushing’s Disease)- second commonest
Adrenal - rare
Ectopic ACTH Syndrome - rare
How to screen for Cushing’s?
1) 24 hour collections for Urinary Free Cortisol and creatinine.
(a normal result rules out Cushing’s syndrome)
2) Overnight 1mg Dexamethasone Suppression Test.
(this should result in a low cortisol level less than 50nmo/L in patients without Cushing’s)
3) Midnight salivary cortisol.
(This should naturally be low at midnight in people without Cushing’s)
What is the confirmatory test for Cushing’s?
Low Dose Dexamethasone Suppression:
Dexamethasone 0.5 mg po q6h x 2 days
Measure 24 hr urinary free cortisol levels
Lack of Suppression = Cushing’s Syndrome
What are some tests that can be carried if you suspect expect glucocorticoid excess from a pituitary tumor?
High Dose Dexamethasone suppression test (Pituitary tumours will respond to high dose dexamethasone and result to a lower cortisol) –> followed by MRI
CRH Test (Pituitary Tumours will respond to CRH)
True or False: Serum cortsiol is a good test for Cushing’s
False: usually shows normal cortisol (24 hrs urine is better as it shows increase)
True or False: oral contraceptives will increase serum cortisol
True: estrogen increases number of cortisol binding protein which increases serum cortisol BUT 24 hrs urine cortiosl is normal as it measures free and unbound cortisol.
