Ectopic adrenocorticotropic hormone (ACTH) syndrome in a patient with medullary thyroid carcinoma is a rare complication, and is associated with a significant mortality risk. We report the case of a gentleman with established metastatic medullary thyroid carcinoma who presents with features of ectopic ACTH syndrome.
A 61 year old gentleman presented with a syncopal episode and was found to be severely hypokalaemic (K+1.0mmol/L) with an associated metabolic alkalosis and hypochloraemia. He had a total thyroidectomy and central neck dissection followed by radioactive iodine the year prior for metastatic medullary thyroid carcinoma with evidence of pulmonary metastases. He had an elevated urinary free cortisol of 3944nmol/24hrs (N:50-250) and an elevated ACTH of 48.8 pmol/L (N:0-12).
Bilateral adrenalectomy was considered in view of the risk of infections associated with being in the immunosuppressed state however the patient was deemed too unwell for surgery and was commenced on medical blockade therapy with Metyrapone. The patient subsequently developed Streptococcus Pneumoniae pericarditis with a pericardial effusion requiring drainage, along with a Klebsiella Pneumoniaebactaraemia. He continued to deteriorate and eventually passed away.
This case highlights the high morbidity and mortality associated with ectopic ACTH syndrome from medullary thyroid cancer, which is reported in 0.6% of cases.