Indication to dynamic and invasive testing in Cushing's disease according to different neuroradiological findings

PURPOSE

Dynamic testing represents the mainstay in the differential diagnosis of ACTH-dependent Cushing's syndrome. However, in case of undetectable or detectable lesion < 6 mm on MRI, bilateral inferior petrosal sinus sampling (BIPSS) is suggested by current guidelines. Aim of this study was to analyze the performance of CRH, desmopressin and high-dose dexamethasone suppression test (HDDST) in the differential diagnosis of ACTH-dependent Cushing's syndrome as well as the impact of invasive and noninvasive tests on surgical outcome in patients affected by Cushing's disease (CD).

METHODS

Retrospective analysis on 148 patients with CD and 26 patients with ectopic ACTH syndrome.

RESULTS

Among CD patients, negative MRI/lesion < 6 mm was detected in 97 patients (Group A); 29 had a 6-10 mm lesion (Group B) and 22 a macroadenoma (Group C). A positive response to CRH test, HDSST and desmopressin test was recorded in 89.4%, 91·4% and 70.1% of cases, respectively. Concordant positive response to both CRH/HDDST and CRH/desmopressin tests showed a positive predictive value of 100% for the diagnosis of CD. Among Group A patients with concordant CRH test and HDDST, no difference in surgical outcome was found between patients who performed BIPSS and those who did not (66.6% vs 70.4%, p = 0.78).

CONCLUSIONS

CRH, desmopressin test and HDDST have high accuracy in the differential diagnosis of ACTH-dependent CS. In patients with microadenoma < 6 mm or non-visible lesion, a concordant positive response to noninvasive tests seems sufficient to diagnose CD, irrespective of MRI finding. In these patients, BIPSS should be reserved to discordant tests.

Dexamethasone measurement during low-dose suppression test for suspected hypercortisolism: threshold development with and validation

BACKGROUND AND AIM

Dexamethasone Suppression Test (DST), recommended for Cushing's Syndrome (CS) diagnosis, explores the pituitary feedback to glucocorticoids. Its diagnostic accuracy could be affected by dexamethasone bioavailability, and therefore, we have developed and validated a dexamethasone threshold after 1-mg DST.

MATERIALS AND METHODS

We studied 200 subjects: 125 patients were considered retrospectively and 75 were enrolled prospectively as the validation cohort. Serum dexamethasone, Late Night Salivary Cortisol (LNSC), and Urinary Free Cortisol (UFC) were measured with LC-MS/MS. Normal LNSC and UFC levels were used to exclude CS. The lower 2.5th percentile of dexamethasone distribution in non-CS patients with cortisol ≤ 50 nmol/L after 1-mg DST was used as threshold.

RESULTS

16 patients were CS and 184 non-CS (108 adrenal incidentaloma and 76 excluded CS); 4.5 nmol/L resulted the calculated threshold. Cortisol after 1-mg DST confirmed high sensitivity (100% at 50 nmol/L cut-off) and moderate-low specificity (63%, increased to 91% at 138 nmol/L) to diagnose CS in the whole cohort of patients. We could reduce the number of false-positive results (from 10 to 6 and from 7 to 4 in AI and excluded CS) considering adequate dexamethasone levels. Dexamethasone levels were not affected by hypercortisolism, age, gender, smoke, weight, and creatinine. 6% of non-CS patients did not achieve adequate dexamethasone levels (40% of tests with serum cortisol > 138 nmol/L after 1-mg DST).

CONCLUSIONS

We developed and validated the routine dexamethasone measurement during 1-mg DST: it is independent from patient's clinical presentation, and it should be used to increase the specificity of serum cortisol levels.

Perioperative multidisciplinary management of endoscopic transsphenoidal surgery for sellar lesions: practical suggestions from the Padova model

Perioperative management of patients with sellar lesion submitted to endoscopic transsphenoidal neurosurgery (TSS) lacks standardization and therefore it is committed to each center clinical practice. Although neurosurgical procedure remains the same for all sellar lesions, perioperative approach can require different measures depending on the underlying disease. With the aim of standardizing our perioperative procedures and sharing our experience with other centers involved in the management of pituitary disease, we developed a clinical care path for patients with sellar lesions candidate to endoscopic TSS. For the drafting of the following protocol, the national and international guidelines published in the last 5 years have been evaluated and integrated with our center experience accumulated in decades of clinical practice. A steering committee including medical doctors involved in management of patients with pituitary masses at the Padua Hospital reviewed current knowledge on this topic. The committee developed a first draft which was shared with a broader group of medical doctors to reach a preliminary consensus; when it was reached, the clinical care assistance pathway was confirmed, validated, and published in the local web-based health service. We want to present and share our experience with colleagues involved in the perioperative management of pituitary diseases in other centers.

Medical Treatment for Acromegaly does not Increase the Risk of Central Adrenal Insufficiency: A Long-Term Follow-Up Study

Central adrenal insufficiency (CAI) in acromegaly may be related to pituitary adenoma or induced by various medical treatments, transsphenoidal neurosurgery (TNS) or radiotherapy (RT), alone or combined. We assessed the role of all available treatments for acromegaly in inducing CAI. We retrospectively studied 97 patients. CAI was diagnosed if morning serum cortisol was <138 nmol/l, or if its response was inadequate in the low-dose short synacthen test. Seventy-four subjects underwent TNS (and 17 of whom also underwent RT), and 23 were on primary medical therapy: overall we diagnosed 21 cases of CAI. Duration of acromegaly, invasion of cavernous sinus, disease control, and type of medical treatment were much the same for patients with and without CAI, which was identified in 18% of patients (10/57) after one TNS, and in 53% (9/17) after RT (p=0.01); repeat surgery increased the risk of CAI (p=0.02). The risk of CAI onset during the follow-up was lower among patients treated with TNS or medical therapy than after RT (p=0.035). Medical treatment did not raise the risk of CAI, whereas a 5- and 4-fold higher risk of CAI was associated with repeat TNS and RT, respectively. Basal or stimulated cortisol levels were similar among acromegalic patients without CAI and matched controls with nonsecreting pituitary lesions. A significant proportion of patients with acromegaly developed CAI over time. While primary or secondary medical treatment did not contribute to the risk of CAI, repeat TNS and RT correlated with pituitary-adrenal axis impairment.