Cushings syndrome

Question 1

How to diagnosis cushing’s syndrome

Answer 1

need to confirm abnormal results on TWO separate screening tests Then establish etiology of high cortisol

Question 2

screening tests for cushing’s disease

Answer 2

low dose dexamethasone suppression test 24hr urine free cortisol assay late night salivary cortisol assay

Question 3

after you have two abnormal levels of cushings disease, you need to differentiate etiology

Answer 3

is this ACTH dependent or ACTH independent check a plasma ACTH level

Question 4

ACTH independent Cushing’s syndrome lab level

Answer 4

<5 pg/ml see cortisol secreting adrenal mass or adrenal hyperplasia and so look for adrenal glands via imaging

Question 5

ACTH DEPENDENT Cushings syndrome lab results

Answer 5

High ACTH look for a ACTH secreting pituitary adenoma (Cushings dx) rather than an ectopic screening ACTH tumor (cancer)

Question 6

If you have ACTH dependent process and see high ACTH on plasma what test do you order next?

Answer 6

order a high dose cortysintropin test suppression test. Can also check cortisol levels after a high dose dexamethasone suppression test (8 mg) to suppress ACTH. In extrapituitary or exogenous ACTH tumors there will be no suppression with the high dose steroids when you recheck cortisol levels.

Question 7

ectopic cancers that can secrete ACTH are:

Answer 7

medullary thyroid cancer, SCLC, GI tract, phenochromocytoma and rarely prostate.

Question 8

work up for cushings syndrome

Answer 8

Question 9

States of high cortisol that don’t necessarily need a Cushing’s syndrome evaluation

Answer 9

pregnancy,

uncontrolled DM2

chronic ETOH use

obese people

use of high steroids.

Lack of obesity but will have high cortisol level: malnutrition, high exercise and amenorrhea

Question 11

A POSITIVE 1 mg overnight dexamethasone supprestion test is

Answer 11

if morning cortisol level is >5 mg then it’s positive.

the 1mg dexamethasone test is supposed to suppress cortisol so that it’s less than 5. if greater than 5, it means that there’s extra cortisol being produced.

Question 12

best screening test for cushings if pt is a third shift worker and on OCPs?

24 hr urine cortisol

late night salivary cortisol level

1mg dexamethasone suppression test

Answer 12

24 hr urine cortisol level is better.

the diurnal cortisol levels will be messed up if you work at night so can’t get a late night salivary cortisol test

also OCPS lead to an increase in cortisol binding proteins and so will have skewed serum cortisol measuremetn .