Category: Pituitary Disorders/Neuroendocrinology

Type: e-Poster

Monitor: 9

9 - A PROPOSAL TO IMPROVE AND UTILIZE VERY HIGH DOSE DEXAMETHASONE SUPPRESSION TEST IN THE ETIOLOGIC DIAGNOSIS OF CUSHING'S SYNDROME

Thursday, Apr 25
1:00 PM – 1:30 PM

Objective : To improve very high dose dexamethasone (dex) suppression test.


Methods : Very high dose dex suppression test entails dex 32 mg/day given as 8 mg po q6h. 50% suppression of both serum and 24 h urine free cortisol indicates a pituitary source.


Results : Case-1: 36-year-old male with abnormal overnight dex suppression had no serum and 24 h urine free cortisol suppression with 2-day 8 mg high dose dex suppression test suggesting ectopic source. There was no mass on chest CT. Pituitary MRI showed 6 mm microadenoma. 32 mg very high dose dex suppression for one day showed basal cortisol: 33 mcg/dl, ACTH: 262 pg/ml, 24 h urine free cortisol: 712 mcg/day, post-test cortisol: 13 mcg/dl, ACTH: 70 pg/ml, 24 h urine free cortisol: 1287 mcg/day. ACTH and cortisol suppressed > 50%, but 24 h urine free cortisol increased. IPSS showed hypophysis/peripheral ACTH basally over 2, and post-CRH stimulation over 3. A pituitary adenoma with a positive ACTH immunohistochemistry was extirpated at transsphenoidal intervention. Post-op hypercortisolism improved. Case-2: 55-year-old woman with history of successful transsphenoidal surgery for Cushing’s disease in 2000 had symptoms of hypercortisolism in the last three years. She had abnormal overnight dex suppression and had no serum cortisol and 24 h urine free cortisol suppression with 2-day high dose dex suggesting ectopic source. There was no mass on chest CT. Pituitary MRI initially showed possible 2 mm microadenoma, and abdominal MRI 1.5 cm left adrenal adenoma. 32 mg dex suppression for two days showed basal cortisol: 25 mcg/dl, basal 24 h urine free cortisol: 185 mcg/day, post-test cortisol 0.7 mcg/dl, 24 h urine cortisol less than 0.8 mcg/dl, below the detection limit. IPSS showed hypophysis/peripheral ACTH basally over 2 and post-CRH stimulation over 3. Repeat MRI didn’t show a clear-cut pituitary adenoma, and she was started on ketocanazole.


Discussion : In the first case, one day of 32 mg dex suppressed serum cortisol, but not the urine cortisol, probably due to relatively large mass of the adenoma secreting high amounts of cortisol and short duration of dex administration. Two days of 32 mg dex in the second case suppressed both serum and 24 h urine cortisol.


Conclusion : In cases with ACTH dependent Cushing’s syndrome who do not suppress with 8 mg high dose dex suppression test, 32 mg very high dose dex suppression test should be considered, especially if imaging is positive for a pituitary adenoma and negative for an ectopic source. Very high dose dex suppression test should not be done for one day as previously suggested, but over two days. Very high dose dex suppression test should be considered in the diagnostic algorithm before IPSS.

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Ahmet S. Can

Program Director and Faculty
Arnot-Ogden Medical Center, Lake Erie School of Osteopathic Medicine
Horseheads, New York

Ahmet Selcuk Can, MD went to medical school in Istanbul Faculty of Medicine and graduated in 1989. He did his internship and residency in internal medicine in Cabrini Medical Center affiliated with New York Medical College, in New York City between 1994 and 1996. He completed his Endocrinology Fellowship in Weill Cornell Medicine and Memorial Sloan-Kettering Cancer Center combined program. During his fellowship, he worked in inborn errors of steroid metabolism and published a paper about molecular genetics of 5 alpha reductase deficiency. After fellowship, he worked in various Hospitals and Universities in Turkey. He published about prevalence of the metabolic syndrome and on the sensitivity and specificity of the thyroid fine needle aspiration biopsies. Before joining to Arnot-Ogden Medical Center in Elmira, New York, he worked in a private practice and had affiliations in the Community Medical Center, in Toms River and Ocean Medical Center in Brick, New Jersey and after that worked as a Professor of Medicine in Termal Vocational School in Yalova, Turkey. He has 20 publications in peer-reviewed journals. He serves as the Program Director for Endocrinology, Diabetes and Metabolism Fellowship at Arnot-Ogden Medical Center in Elmira, NY, affiliated with Lake Erie School of Osteopathic Medicine.

Ahmet S. Can

Program Director and Faculty
Arnot-Ogden Medical Center, Lake Erie School of Osteopathic Medicine
Horseheads, New York

Ahmet Selcuk Can, MD went to medical school in Istanbul Faculty of Medicine and graduated in 1989. He did his internship and residency in internal medicine in Cabrini Medical Center affiliated with New York Medical College, in New York City between 1994 and 1996. He completed his Endocrinology Fellowship in Weill Cornell Medicine and Memorial Sloan-Kettering Cancer Center combined program. During his fellowship, he worked in inborn errors of steroid metabolism and published a paper about molecular genetics of 5 alpha reductase deficiency. After fellowship, he worked in various Hospitals and Universities in Turkey. He published about prevalence of the metabolic syndrome and on the sensitivity and specificity of the thyroid fine needle aspiration biopsies. Before joining to Arnot-Ogden Medical Center in Elmira, New York, he worked in a private practice and had affiliations in the Community Medical Center, in Toms River and Ocean Medical Center in Brick, New Jersey and after that worked as a Professor of Medicine in Termal Vocational School in Yalova, Turkey. He has 20 publications in peer-reviewed journals. He serves as the Program Director for Endocrinology, Diabetes and Metabolism Fellowship at Arnot-Ogden Medical Center in Elmira, NY, affiliated with Lake Erie School of Osteopathic Medicine.