Performance of the Overnight Dexamethasone Suppression Test in an Unselected Adrenal Incidentaloma Population; Impact of New European Guidance

Presentation Number: SUN 395
Date of Presentation: April 2nd, 2017

Arun M A Vijay*1, Feaz Babwah1, Sushuma Kalidindi1, Cherian George1, Julian Waldron1, Chris Day1, John Oxtoby1, Gill Powner1, Jessica Hawarden1, Fahmy WF Hanna1 and Anthony A Fryer2
1University Hospitals of North Midlands NHS Trust, United Kingdom, 2University Hospitals of North Midlands NHS Trust, Stoke-on-Trent, United Kingdom

Abstract

INTRODUCTION

Adrenal Incidentaloma (AI) evaluation is a common referral to the Endocrinology department. Although most are regarded as benign and asymptomatic in nature, there is no clear diagnostic pathway and is a cause of anxiety to patients. Our aim was to examine the performance of overnight dexamethasone testing (ODST) in this setting using the cut-off levels proposed in the new guidance1.

METHODS

We retrospectively examined 200 AI patients who had an ODST between 2014-16. Adequate suppression was defined as a 9am cortisol ≤ 50 nmol/l. Demographics, Radiological and Biochemical tests were analysed.

RESULTS

In this group of 200 AI cases, the average age was 66.35 ± 12.23 (mean ± SD) with 60.5% being females. 51.5% patients had hypertension and 24% had diabetes. The lesions were left sided in 59% and bilateral in 15%. The majority of the AI (70.3% of n=236) were characterized on CT imaging (HU <10 or >50% wash-out) to be benign. A minority (6.5%) of lesions were >4cm in size.

Cortisol suppressed adequately in 47.2% of patients on ODST. The unsuppressed cases (n=104, 52.8%) had a mean cortisol value of 120.6 ± 117.0. Of this group, 75% had a cortisol value between 51 and 138 nmol/l consistent with ‘possible autonomous cortisol secretion’ as defined in the new guidelines1. Only 8% of all AI cases had a cortisol value of above 138 nmol/l, consistent with the definition of ‘autonomous cortisol secretion’1. The vast majority (77.6%, n=49) showed consistent results on repeat testing.

LDDST was performed on 94 patients who failed to suppress on ODST. The majority of these (67%) also had inadequate suppression. Of the unsuppressed cases the mean cortisol value was 122.5 ± 121.5. Repeat testing showed consistent results in 87.5% (n=16). UFC sampling done in sync with the LDDST revealed only 12 out of 83 patients (14.5%) with an excretion of >130 nmol/24hr.

CONCLUSION

  • The ODST remains a useful and convenient first-line investigation in the evaluation of patients with AI.
  • In our cohort, the failure of complete suppression on ODST was more prevalent than previously documented (52.8% vs up to 30% in the literature2).
  • Using the proposed cut-off value of < 50 nmol/l will inevitably lead to further testing and additional workload (cascade effect3), while promoting increased anxiety in a large number of these asymptomatic patients.
  • Repeat testing of both ODST and LDDST yielded similar results in the majority of patients demonstrating good reproducibility.
  • The majority of patients who were unsuppressed on ODST remained unsuppressed on LDDST testing with similar mean cortisol values.
  • UFC sampling did not provide additional information to aid in the management of our adrenal incidentaloma patients and perhaps can be omitted.
  • Patients with ‘possible autonomous cortisol secretion’ require further evaluation taking into consideration age and comorbidities, such as diabetes and hypertension, to guide management.

 

Nothing to Disclose: AMAV, FB, SK, CG, JW, CD, JO, GP, JH, FWH, AAF