Endocrine Abstracts

A 39-year-old man was referred to the endocrinology clinic with a suspected phaeochromocytoma. He had a history of hypertension, episodic flushing and erectile dysfunction. He denied any recreational drugs abuse. His past medical history included primary hypogonadism of unknown cause and hypertension. He was on ramipril 5 mg od, atenolol 50 mg od and susatnon injections.

Clinical examination was unremarkable away from BMI of 35, facial flushing and raised blood pressure of 168/105 with no postural drop. He had no cushingoid features. He had no family history of any endocrine disorder.

Biochemical investigations revealed elevated 24 h urinary noradrenaline levels on four occasions (574–1036 nmol/24 h, normal range 0–530 nmol/24 h) and normal adrenaline and dopamine levels. His thyroid function tests, dexamethasone suppression test, rennin/aldosterone ratio, and chromogranin-A were all normal. Abdominal CT and MRI scans were normal and an I123 MIBG scan was also normal.

On further questioning, he admitted to a long history of loud snoring and day time somnolence. Subsequently, an overnight polysomnography showed sever degree of sleep apnoea with aponea/hypopnea index (AHI) score of 52.

Following 6 months of CPAP treatment his urinary noradrenaline levels normalised and persisted during 2 years of follow up. His blood pressure is better controlled and he is off testosterone replacement and enjoying normal libido and erectile function.

The link between sleep apnoea and raised urinary catecholamines in the absence of adrenal or extradrenal phaeochromocytoma has been recognized since 1987. Only few publications have addressed the prevalence of the condition and the possible underlying pathophysiology. None of the reported cases had persistent hypertension, hypogonadism, and raised catecholamine excretion as the presenting features. Our case demonstrates the importance of considering OSA as a possible cause of pseudophaechromocytoma; it also highlights the impact of CPAP treatment on patients’ hypertension, erectile dysfunction and urinary catecholamine.