Endocrine Abstracts

A 12-year-old girl presented with dizziness, palpitations, headaches and sweating associated with hypertension (170/100 mmHg) and tachycardia (180 beats per minute). Repeated urinary and serum catecholamines were initially unremarkable. Routine biochemical and haematological testing was normal as were serum gut peptides. The patient was commenced on phenoxybenzamine, nifedipine and propranolol. This improved her symptoms, and corrected her tachycardia and raised blood pressure.

Further investigations were performed. A CT scan of her abdomen was normal. An MIBG scan demonstrated bilaterally increased adrenal uptake suggesting bilateral phaechromocytoma or adrenal medullary hyperplasia. Inferior vena caval sampling was carried out for catecholamines. This showed raised noradrenaline (11.1 nmol/l, NR=0.15–3.5 nmol/l) and adrenaline (12.8 nmol/l, NR=0.1–0.8 nmol/l). The patient underwent bilateral adrenalectomy. The histology of the adrenal glands however did not show any evidence of phaeochromocytoma.

Post-operatively she was commenced on adrenal replacement therapy. Attempts were made to stop her anti-hypertensive medication. On stopping propranolol however she developed a relapse of her symptoms, predominantly on standing. Repeated testing demonstrated persistently elevated urinary noradrenaline levels. She underwent further imaging- including MIBG scanning, octreotide scanning, MRI scanning and Uultrasound scans of carotids and bladder. The results were normal with no evidence of residual phaeochromocytoma.

Postural serum catecholamine testing revealed normal noradrenaline levels while supine 2.9 nmol/l (N 4.1–5.6) but elevated levels on standing (5.7 nmol/l) Administration of Pentolinium produced a reduction in standing noradrenaline from 5.1 to 2.3 nmol/l.

These results indicate a neural control of noradrenaline release, suggesting a diagnosis of noradrenaline reuptake disorder. The patient was recommenced on a combination of Doxazosin and Propranolol. She is now symptom-free and 24 h cardiac monitoring confirms an adequate control of pulse and blood pressure.

When clinical and biochemical features of phaeochromocytoma occur predominantly on standing, the diagnosis of a catecholamine reuptake disorder should be considered.