Endocrine Abstracts

Introduction-

Cushing's syndrome is characterised by hypercortisolaemia, loss of the diurnal rhythm of cortisol secretion and loss of negative hypothalamic-pituitary-adrenal (HPA) feedback. Patients with adrenal incidentalomas may manifest some signs of cortisol excess before developing overt Cushing's syndrome. This can be considered as 'Cushing's syndrome in evolution'.

Case History-

A 47 year old lady with type 2 diabetes, hypertension, facial plethora and hirsuitism was found to have a 2 cm left adrenal incidentaloma on CT scan. She had no thin skin, bruising or proximal myopathy. Twenty-four hour urine free cortisol levels were normal and 0900h cortisol following 1mg overnight dexamethasone (ONDST) was 39.8nmol/l (normal<50nmol/l). 0900h ACTH measured 13.7ng/l (range 9-51ng/l). Daytime and midnight cortisol were within normal reference ranges.

Twelve months later the adrenal lesion had grown to 3 cm. The patient developed congestive cardiac failure and diabetic control deteriorated. Following repeat ONDST 0900h cortisol measured 26.4 nmol/l.

Six months later the patient developed proximal myopathy and ONDST showed a 0900 h cortisol of 45.8 nmol/l. Urine free cortisol was elevated 575 nmol/24 h (normal< 290nmol/24h). ACTH measured 14.1ng/l. Following 48 hr low dose dexamethasone suppression testing 0900h cortisol measured 15.0nmol/(normal<50nmol/l). Fifteen minutes post CRH administration cortisol suppressed to 13.0nmol/l (normal < 38nmol/l)

Iodocholesterol scanning showed increased uptake in the left adrenal. The patient proceeded to laparoscopic adrenalectomy, where a 3 cm left adrenal mass was removed. Histology revealed an adrenocortical adenoma. Post-operative assessment showed contralateral adrenal suppression.

Discussion-

In this patient hypercortisolaemia evolved over a period of time in concurrence with an enlarging adrenal tumour. Although our patient did not fulfil the diagnostic criteria for Cushing's syndrome, adrenocortical hyperfunction was demonstrated and surgical removal of the lesion was advocated.