Dx and Tx of Cushing's Syndrome

Question 1

what are cortisol levels like?

Answer 1

they vary throughout the day (follow the circadian rhythm) so random blood samples cannot Dx it

Question 2

what diagnostics could you do?

Answer 2

• urine sample (24 hr sample accounts for fluctuations in levels)
• CT and MRI for adrenal tumor prod cortisol, pituitary tumor prod ACTH, or ectopic tumor

Question 3

serum and salivary cortisol

Answer 3

must take the time of day that the sample was taken into account

Question 4

dexamethasone suppression test

Answer 4

• man-made glucocorticoid (
• Has a similar fx to cortisol, therefore if dexamethasone is administered, ACTH levels should decrease (neg fb) and lead to a decreased cortisol level
• ACTH levels are then measured in the blood, if not lowered then hypersecretion of ACTH (resulting in hypersecretion of cortisol) is evident

Question 5

what is the tx?

Answer 5

1) excise tumor
2) irradiate pituitary
3) ectopic tumor - enzyme inhibitors (suppress hormone but don’t kill tumor) + chemo
4) adrenalectomy (one can be removed; last resort)