Clinical and biochemical characteristics of Cushing' s disease with different suppression rates by high-dose dexamethasone

Abstract

Objective To analyze the clinical and biochemical characteristics of Cushing's disease with differeut suppression rates by high-dose dexamethasone.Methods Two hundred and two consecutive patients with Cushing's disease were divided into three groups according to the response to the high-dose dexamethasone suppression test (HDDST):non-suppressed group (suppression rate ＜50％),suppressed group A (suppression rate ≥ 80％) and suppressed group B (suppression rate 50％-80％).Results (1) Of the 202 patients,non-suppressed group was seen in 23.3％ (47/202),meanwhile suppressed group A and B accounted for 53.4％ and 23.3％ respectively.Compared with both suppressed group A and B,non-suppressed group had shorter duration and lower serum potassium level(P＜0.01).(2) Patients in non-suppressed group presented a higher prevalence of striae,edema of lower limbs and disorder of glucose metabolism as compared with the patients in suppressed group A.On the other hand,patients in non-suppressed group were more likely to suffer from hypertension and hypokalemia than those in both suppressed group A and B.Further analysis of prevalence of hypokalemia in suppressed group revealed significantly higher prevalence rate of hypokalemia in suppressed group B (P＜0.05).(3) Patients in non-suppressed group also had significantly higher baseline plasma ACTH,cortisol,and 24 h urinary free cortisol than those in both suppressed group A and B.Patients in suppressed group A presented significantly higher baseline plasma cortisol levels (8:00) as compared with patients in suppressed group B.(4) Pituitary MRI revealed no significant difference among the 3 groups,and the direct signs of pituitary tumor were more common in patients with positive pituitary imaging.Bilateral hyperplasia was the most common imaging feature of adrenal glands,and it tended to be more common of patients in non-suppressed group.No significant difference was found in findings of normal-like adrenal gland among three groups.However,unilateral hyperplasia was more common on the left,especially in the suppressed group A.Conclusion There were no significant differences in the clinical and biochemical characteristics of Cushing's disease in both suppressed group A and B,except for a significant higher serum cortisol at 8:00 and prevalence of hypokalemia in suppressed group B.The patients in non-suppressed group presented higher levels of the hormone,shorter duration,more typical signs of Cushing' s disease and severe biochemical abnormalities as compared with suppressed groups. Key words: Cushing's disease; High-dose dexamethasone suppression test; Clinical manifestations; Imaging features