A Wolf in Sheep’s Clothing - Hyperadrenalism with a hypoadrenal profile.

Demelza Vinnicombe, Nina Wietek, Gemma Hopkins, Alex Sumption, Roaa Al-Bedaery, Rabia Topan, Sagen Zac-Varghese, Stephen Robinson, Rami Fikri, Jeremy Cox.


Mr VM, an 81 yr old ♂ presented to his GP feeling unwell. Initial GP investigations had revealed hyperkalaemia, hyponatraemia and, the patient was found to be hypotensive. Thus the GP had initiated steroid replacement for presumed hypoadrenalism and called St Mary’s Hospital for endocrine advice. The steroids (prednisolone 10 mg) led to a marked subjective improvement in symptoms and the patient was slightly resistant to being brought in to hospital for further assessment.

On admission, the patient was clinically dehydrated, was found to have a high output ileostomy and had a significant postural drop in blood pressure. His past medical history included metastatic bowel cancer, chronic kidney disease, atrial fibrillation and hypertension.

Initial investigations confirmed hyponatraemia and hyperkalaemia, however, further endocrine investigations demonstrated normally functioning adrenal glands with a normal short synacthen test and elevated levels of renin and aldosterone. Hypoadrenalism was considered unlikely in this context.

Thus, in spite of the blood profile it was felt that the most likely diagnosis was

1. Dehydration secondary to high output ileostomy,

2. Loss of salt and fluid leading to hyponatraemia and a secondary increase in renin and aldosterone

3. Renal failure leading to hyperkalaemia           

The patient was rehydrated with intravenous saline and was reviewed by the stoma nurse. He was discharged on sodium bicarbonate 1g BD for further outpatient review by the renal team.

Learning points:

1. The initial decision to initiate steroids was logical as the electrolyte profile was in line with a diagnosis of hypoadrenalism (given the metastatic bowel cancer, adrenal involvement was possible);

2. Appropriate endocrine investigations allowed determination of the true cause of the electrolyte disturbance (the high output ileostomy, causing severe dehydration and leading to activation of normal physiological mechanisms to conserve salt and water).