Non-invasive Diagnostic Strategy in ACTH-dependent Cushing's Syndrome

J Clin Endocrinol Metab. 2020 Oct 1;105(10):dgaa409. doi: 10.1210/clinem/dgaa409.


Context: Inferior petrosal sinus sampling (IPSS) is used to diagnose Cushing's disease (CD) when dexamethasone-suppression and CRH tests, and pituitary magnetic resonance imaging (MRI), are negative or give discordant results. However, IPSS is an invasive procedure and its availability is limited.

Objective: To test a noninvasive diagnostic strategy associated with 100% positive predictive value (PPV) for CD.

Design: Retrospective study.

Setting: Two university hospitals.

Patients: A total of 167 patients with CD and 27 patients with ectopic ACTH-syndrome investigated between 2001 and 2016.

Main outcome measure(s): Performance of a strategy involving the CRH and desmopressin tests with pituitary MRI followed by thin-slice whole-body computed tomography (CT) scan in patients with inconclusive results.

Results: Using thresholds of a cortisol increase > 17% with an ACTH increase > 37% during the CRH test and a cortisol increase > 18% with an ACTH increase > 33% during the desmopressin test, the combination of both tests gave 73% sensitivity and 98% PPV of CD. The sensitivity and PPV for pituitary MRI were 71% and 99%, respectively. CT scan identified 67% EAS at presentation with no false-positives. The PPV for CD was 100% in patients with positive responses to both tests, with negative pituitary MRI and CT scan. The Negative Predictive Value was 100% in patients with negative responses to both tests, with negative pituitary MRI and positive CT scan. Using this strategy, IPPS could have been avoided in 47% of patients in whom it is currently recommended.

Conclusions: In conjunction with expert radiologic interpretation, the non-invasive algorithm studied significantly reduces the need for IPSS in the investigation of ACTH-dependent Cushing's syndrome.

Keywords: CRH test; CT scanning; Cushing’s disease; bilateral inferior petrosal sinus sampling; desmopressin test; ectopic ACTH-syndrome.

Publication types

  • Evaluation Study
  • Multicenter Study

MeSH terms

  • ACTH Syndrome, Ectopic / blood
  • ACTH Syndrome, Ectopic / diagnosis*
  • ACTH Syndrome, Ectopic / etiology
  • ACTH Syndrome, Ectopic / surgery
  • Adolescent
  • Adrenocorticotropic Hormone / blood
  • Adrenocorticotropic Hormone / metabolism
  • Adult
  • Aged
  • Aged, 80 and over
  • Algorithms
  • Deamino Arginine Vasopressin / administration & dosage
  • Decision Support Techniques*
  • Diagnosis, Differential
  • Female
  • Humans
  • Hydrocortisone / blood
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neuroendocrine Tumors / blood
  • Neuroendocrine Tumors / complications*
  • Neuroendocrine Tumors / pathology
  • Petrosal Sinus Sampling / adverse effects
  • Pituitary ACTH Hypersecretion / blood
  • Pituitary ACTH Hypersecretion / diagnosis*
  • Pituitary ACTH Hypersecretion / pathology
  • Pituitary ACTH Hypersecretion / surgery
  • Pituitary Function Tests / methods
  • Pituitary Gland / diagnostic imaging
  • Pituitary Gland / drug effects
  • Pituitary Gland / pathology*
  • Pituitary Gland / surgery
  • Predictive Value of Tests
  • Retrospective Studies
  • Tomography, X-Ray Computed
  • Young Adult


  • Adrenocorticotropic Hormone
  • Deamino Arginine Vasopressin
  • Hydrocortisone