Endocrine Abstracts

48 year-old woman was referred to the endocrine clinic by the respiratory team for management of an incidental 2cm right adrenal mass found on chest/upper abdomen computed tomography (CT) as part of investigations for recurrent chest infections. On review, she described attacks of ' doom and gloom', flushing and palpitations with a rate of 140 beats per minute. The attacks were sporadic and occurred for some years. Blood pressure in the endocrine clinic was 210/110. Urea and electrolytes, testosterone, androstenedione, DHEAS were normal. An over-night dexamethasone suppression test excluded Cushing's syndrome. Three urine catecholamine/creatinine ratios were normal. The patient's symptoms and blood pressure were improved by labetalol 200 mg twice daily. During investigations the patient had measurement of urinary catecholamine/creatinine ratios on 13 occasions. All, but one, were within normal limits. One revealed a urinary adrenaline/creatinine ratio of 11 micromol per mmol (Normal Range: 0-10). 24 hours urine metanephrines, plasma catecholamines and 24 hours urinary catecholamines were also normal. A repeat abdominal CT showed no change. As the patient's symptoms persisted, an MIBG scan was arranged. MIBG showed marked uptake in the right adrenal consistent with a phaechromocytoma.

Repeat urine catecholamine/creatinine ratios at another centre were again normal. After discussion with the patient, she was started on phenoxybenzamine and propranolol and a laparoscopic right adrenalectomy was performed. The patient was discharged from the hospital after 48 hours off all medications, normotensive and symptom free. Histological examination showed typical appearances of a 8 cm phaechromocytoma with central cystic degeneration.

Stimulation tests were not done in this patient, as it was felt that it would not change the management. They are rarely used nowadays as they can precipitate an adrenergic crisis.

The case represents a reminder that urine and plasma catecholamines can be normal in patients with symptomatic phaeochromocytoma.