EVALUATION OF PATIENTS FOR SUSPECTED CUSHING'S SYNDROME

Clinical symptoms and/or Signs

24 hour urine collection (may repeat 2-3 times)

Measure creatinine and cortisol

Adequate Collection Creatinine 15-25 MG/KG/DAY

Normal Urinary Cortisol < 40µgram/day

Low Dose Dexamethasone

Suppression Test:0.5mg po q6 houts for 8 doses

OR

Overnight Test with 1mg

Dexamethasone at 11:00 PM

Corticotropic(ACTH) Dependent vs. Independent Cushing's

Measure Late Afternoon or Evening Plasma ACTH and Cortisol Levels

Normal ACTH: 5-15 pg/ml

Suppressed ACTH: <5pg/ml

Elevated ACTH:> 15pg/ml

High Dose Dexamethasone Suppression Test:

2 mg q6^* for 8 doses

Ectopic ACTH Secretion

Cushing's Disease

Measure 8:AM Serum Cortisol

Normal < 5µgram/dl(< 138nMol)

Measure 24 hour Urine Cortisol in last 24 hours of test

Normal < 10 µgram

OR

Measure 24 hour Uring 17-hydroxycorticosteriod level

Normal < 2.5mg/d(< 6.9 µgramMol)

Normal Cortisol

Cushing's Syndrome

Slight Elevation

Elevated ACTH:

Pituitary (Crushing's Disease) vs. Ectopic Secretion

Depressed ACTH:

Ectopic Cortisol Prosuction -> CT or MRI

Failed Suppression

>90% Suppression of Basal

24 hour Urinary Cortisol

OR

>64% Suppression of Basal 17 hydroxycorticosteroids

Normal

Elevated Levels

END