Clinical Characteristics of Endogenous Cushing’s Syndrome at a Medical Center in Southern Taiwan

Table 2

Test results for ACTH-independent CS and ACTH-dependent Cushing’s syndrome (CS) in the 84 patients studied.

Tests	ACTH-independent CS% (number of patients)	ACTH-dependent CS% (number of patients)	All patients with CS% (number of patients)	Cushing's disease% (number of patients)	Ectopic CS% (number of patients)
Loss of cortisol circadian
rhythm (+)*	96.4% (53/55)	94.4% (17/18)	95.9% (70/73)
Baseline plasma cortisol levels
at 1600–2200 h > 7.5 μg/dL	98.3% (58/59)	94.4% (17/18)	97.4% (75/77)
Baseline 24 h UFC
>122 μg/24 h	87.5% (35/40)	91.7% (11/12)	88.5% (46/52)
>80 μg/24 h	97.5% (39/40)	91.7% (11/12)	96.2% (50/52)
Overnight LDDST**
0800 h plasma cortisol > 5 μg/dL: nonsuppression	100% (48/48)	88.9% (8/9)	98.2% (56/57)	85.7% (6/7)	100% (2/2)
2-day LDDST^§
0800 h plasma cortisol > 5 μg/dL: nonsuppression	100% (25/25)	100% (7/7)	100% (32/32)	100% (5/5)	100% (2/2)
24 h UFC > 122 μg/day: nonsuppression	100% (15/15)	66.7% (2/3)	94.4% (17/18)	50% (1/2)	100% (1/1)
2-day HHDST^§§
0800 h plasma cortisol
Nonsuppression^†	95.5% (42/44)			55.6% (5/9)	100% (2/2)
Suppression	4.5% (2/44)			44.4% (4/9)
24 h UFC
Nonsuppression^‡	88.9% (24/27)			14.3% (1/7)	100% (1/1)
Suppression	11.5% (3/26)			85.7% (6/7)

∗Loss of cortisol circadian rhythm (+): baseline plasma cortisol levels at 1600–2200 h greater than 7.5 μg/dL and greater than 50% of baseline plasma cortisol levels at 0800–0900 h.
∗∗Overnight LDDST: overnight low-dose dexamethasone suppression test: dexamethasone 1 mg orally at 2300 h and blood sampling for cortisol the following morning at 0800 h.
§2-day LDDST: 2-day low-dose dexamethasone suppression test: dexamethasone 0.5 mg orally every 6 hours for a total of 8 doses and blood sampling for cortisol at 0800 h on the third day of testing. Collection of urine for free cortisol for 24 h from 0800 h on the second day to 0800 h on third day following dexamethasone administration.
§§2-day HDDST: 2-day high-dose dexamethasone suppression test: dexamethasone 2 mg orally every 6 hours for a total of 8 doses and blood sampling for cortisol at 0800 h on the third day of testing. Collection of urine for free cortisol for 24 h from 0800 h on the second day to 0800 h on the third day following dexamethasone administration.
†Nonsuppression of 0800 h plasma cortisol on 2-day HDDST: a cut-off value of 0800 h plasma cortisol after 2-day HDDST is greater than 50% of baseline plasma cortisol.
‡Nonsuppression of 24 h urine free cortisol on 2-day HDDST: a cut-off value of 24 h urinary free cortisol after 2-day HDDST is greater than 50% of baseline 24 h urinary free cortisol.