37 year old gentleman presented with Cushings disease at the age of 15 with obesity, growth retardation, and vertebral fracture. After bilateral adrenalectomy and pituitary irradiation he was treated with hydrocortisone and fludrocortisone. After being lost to follow up for a number of years he was referred to our endocrine clinic in 1999. Clinical examination revealed that he was obese (BMI 39.2), hypertensive and had marked abdominal striae. Investigations revealed an IGF-1 of 14 (15.952 nmol/L), free T4 of 15.1 mmol/L, testosterone of 5.8 (926 nmol/L), LH of 2.1 (110 IU/L), FSH of 2.7 (110 IU/L), ACTH of <5 ng/L and renin levels of 1.5 (0.53.0 pmol/ml). An Insulin tolerance test confirmed that he was Growth Hormone deficient. Cortisol day profiles showed high 9 am values of 369 nmol/L suggesting endogenous production. CT Abdomen showed residual left adrenal tissue. Hydrocortisone is being tailed off under close surveillance.
There are case reports of persistent or recurrent endogenous cortisol production after bilateral adrenalectomy. This residual adreno-cortical function can be caused by either the presence of accessory adrenal tissue or adrenal remnants left behind at surgery. Ectopic adrenal tissue has been demonstrated in 32% of autopsies. Morning plasma cortisol of greater than 50 nmol/L should indicate either residual or accessory adrenal activity. Adrenal remnants occur more frequently at the right side because complete extirpation of the right adrenal gland is technically more difficult.
This case highlights the need to be aware of functioning cortisol producing tissue after bilateral adrenalectomy for pituitary dependant Cushings disease. Lifelong surveillance is therefore needed and substitution steroid replacement should be prescribed on an individual basis.