Cushing's disease Flashcards
When is cortisol bioactive?
Only when it is unbound (Carrier protein, some on albumin). Only about 4% is free.
Signs and symptoms of Cushing’s syndrome
Central obesity (face, neck, trunk) and thin legs/arms; weakness; moon face; massive weight gain (red stretch marks, poorly healed); easy bruising; plethora (red face); mood; hirsuitism; menstrual irrgeularity; ED; hyper pigmentation (ACTH associated); headache (pituitary); thin skin; high BP, diabetes
Causes of Cushings
Iatrogenic - most common (taking steroids for conditions); pituitary tumour (Cushing’s disease); adrenal tumour and ectopic ACTH syndrome (tumours elsewhere that make ACTH) - Rare.
Diagnosing Cushing’s
Good Hx (onset of signs/symptoms). 2 x 24h collections for Urine Cortisol and creatinine (control); or overnight dexamethasone suppression test (taking it should lower cortisol); or midnight salivary cortisol (should be low).
24h urine test
Measures the free cortisol (bioactive). Not so good for adrenal insufficiency.
How to confirm Cushing’s?
Small dose of dexamethasone every 6h for 2 days and measure cortisol. This should shut off production of cortisol. If it doesn’t then diagnosis’s confirmed.
After confirming diagnosis, what next?
Determine what type. Adrenal problem? or Measure ACTH (looking for pituitary or ectopic production). High dexamethasone will suppress pituitary hormone a bit, ectopic will not respond. Can do an MRI on pituitary and test the blood close to the pituitary looking for higher ACTH there (Bilateral Inferior Petrosal Sinus Sampling). Ectopic tumour can be hard to find - PET scan. Chart.
Serum cortisol measure
Not as accurate, 24h urine is better for free cortisol. Oral contraceptive pill can affect the serum cortisol (make it look high by having more bound)
Treatment for Cushing’s
Surgical removal (transsphenoidal pituitary adenomectomy), removal of ectopic ACTH-producing tumor, medical therapy, adrenalectomy
Summary of diagnosing Cushing’s
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