Serial Salivary Cortisol and Desmopressin Stimulation Testing in the Diagnosis of Cyclical Cushing’s

Presentation Number: SAT 418
Date of Presentation: April 1st, 2017

Raquel Villavicencio*1 and Melissa Cavaghan2
1Indiana University School of Medicine, Indianapolils, IN, 2Indiana University School of Medicine, Indianapolis, IN

Abstract

Introduction

Cyclical Cushing’s syndrome (CCS) can be an elusive diagnosis and may go unrecognized for years, even after appropriate endocrine evaluation. We illustrate a case in which serial salivary cortisol levels were used to make the diagnosis of CCS.

Clinical Case

A 36 year old woman presented with one year history of fifty pound weight gain, irregular menses, hirsuitism, irritability, fatigue and proximal muscle weakness. She had already undergone extensive testing, which collectively did not clearly establish Cushing’s. Five of twelve dexamethasone (Dex) suppression tests (DST) were abnormal, ranging from 0.6-6 µg/dL (<1.8). Fourteen of eighteen urine free cortisols (UFC) were elevated, ranging from 29-139.7 µg/24h (4-50). A Dex-CRH test showed a cortisol of 2.9 µg/dL (<1.8) after two days of Dex and 30-minute cortisol peak of 5.7 µg/dL (>20% rise is consistent with Cushing’s disease). However, 48-hr DST suppressed serum cortisol (1.1 µg/dL) and UFC (9.5 µg/24h). She was normotensive (111/55) but obese (81.6 kg, BMI 32.7), with facial plethora, rounded face, subtle cervical fat pads, proximal muscle weakness and mild hypertrichosis. There was no acanthosis nigricans, supraclavicular fat pads, edema, purple striae or hyperpigmentation.

Late night salivary cortisols over ten months were intermittently above normal, ranging from <0.04-0.97 µg/dL (0-0.1), but never long enough for localization testing. During testing, 31% of salivary cortisols were above normal. ACTH levels were never suppressed. MRI showed a 3 mm adenoma in the left inferior aspect of the pituitary gland. A 10 µg desmopressin stimulation test was also performed. ACTH increased by 131% and cortisol increased by 34%, consistent with Cushing’s disease.

At transsphenoidal exploration, intraoperative smear showed a monomorphic population of cells compatible with adenoma. However, final pathology showed adenohypophysis tissue with patchy areas of expanded acini. The cells in these areas stained with ACTH and CM5.2 with the final diagnosis of corticotroph hyperplasia. Post-op day one and two AM cortisols were 33 and 9 µg/dL respectively and she ultimately developed relative adrenal insufficiency which responded to hydrocortisone. Off hydrocortisone, salivary cortisols ranged from undetectable to occasionally elevated, in the range of 0.12-0.19 µg/dL. A repeat desmopressin stimulation test was essentially flat.

Conclusion

Here we demonstrate the effective use of serial salivary cortisols in diagnosing CCS. Second, we illustrate the utility of the desmopressin stimulation test in the work-up of ACTH-dependent Cushing’s syndrome. Although not necessary in the routine evaluation of Cushing’s syndrome, when faced with challenging diagnostic dilemmas such as that presented by CCS, it can be a valuable, additional tool to differentiate between Cushing’s disease and ectopic ACTH secretion.

 

Nothing to Disclose: RV, MC