Catecholamine secreting tumours are rare and as many as 50% are diagnosed post mortem. The clinical features described are of episodic or uncontrollable hypertension and/or symptoms of sympathetic overactivity eg sweating, palpitations, pallor and headache. However, many patients with phaeochromocytoma diagnosed during work-up or follow-up of MEN syndromes are asymptomatic.
There is debate over the most appropriate diagnostic strategy since so few tumours are diagnosed during life, some suggest single 24 h urine collections from all new hypertensive patients whereas others feel that investigations should be directed at those with typical/suggestive symptoms.
The diagnosis is based on increased urinary catecholamine excretion. We recommend two consecutive 24 hour urine collections in order to ensure that patients with episodic secretion are detected. Urine collections must be made into containers containing acid to ensure preservations of catecholamines. Plasma catecholamine measurement is not recommended in view of the false positive stress response.
The optimal diagnostic protocol is to measure both free catecholamines and their metabolites the metanephrines. Some antihypertensive agents may interfere with the analytical methods and the laboratory should be contacted for advise.
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