Endocrine Abstracts

Case presentation: A 34-year-old woman was diagnosed with hypertension from the age of 26 years. She had been investigated in Canada previously and discovered to have a small left adrenal nodule, satisfactory aldosterone and renin levels, but raised urinary free cortisol levels and non-suppressed cortisol levels on overnight 1 mg dexamethasone suppression test. Upon assessment in our service, the patient reported a history of easy bruising and insomnia. Her BMI was 28.1 kg/m² but there were no overt features of hypercortisolism.

Investigations: Two sets of 9 a.m. ACTH levels were 17–20 (reference range, 0–46) ng/lwith cortisol of 517–673 (200–500) nmol/l. The nadir cortisol following overnight and 48-hour low dose dexamethasone suppression tests were 318 and 285 nmol/l, respectively. Paired midnight and morning salivary cortisol levels demonstrated loss of diurnal variation. Aldosterone-renin, plasma metanephrines, androgen profile and DHEA sulfate levels were satisfactory. MRI of the adrenals confirmed a left-sided adrenal adenoma measuring 2.9 x 2.2 cm. The contralateral adrenal was not atrophied. As ACTH was unsuppressed, a dynamic MRI of the pituitary was performed which showed a 4 mm right-sided microadenoma and a central cystic lesion. Pituitary profile was otherwise normal apart from a mildly raised IGF-1 at 312 (71.2–234 ng/ml) with growth hormone nadir at <0.1 ug/lon an oral glucose tolerance test. Genetic screening for multiple endocrine neoplasia was negative. Inferior petrosal sinus (IPSS) sampling demonstrated a raised central-to-peripheral ratio consistent with Cushing’s disease, lateralising to the right side (Table 1).

Management: The patient was pre-treated with Metyrapone followed by trans-sphenoidal resection of pituitary microadenoma. Histology revealed densely granulated corticotroph adenoma with Ki-67 of < 4%. Her 6-week postoperative morning ACTH was 9 ng/land cortisol 43 nmol/l, consistent with biochemical cure. A 3-month postoperative MRI of the pituitary showed no tumour remnant. She remains on hydrocortisone replacement but is otherwise eupituitary.

Conclusion: The presence of an adrenal adenoma in a patient with biochemically confirmed hypercortisolism suggests adrenal Cushing’s syndrome. However, the non-suppressed ACTH and non-atrophied contralateral adrenal gland were clues to the diagnosis of pituitary Cushing’s disease.*ACTH, adrenocorticotrophic hormone (ng/l)