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Acute intermittent porphyria and phaeochromocytoma: shared features

Acute intermittent porphyria (AIP) is rare in Europeans, with an estimated prevalence of 1–2 per 100 000.1 Acute attacks of porphyria cause severe abdominal pain and a range of neurological and other features, including hypertension, tachycardia and excessive sweating. Some of the clinical features of AIP have been attributed to adrenergic hyperactivity.2

Phaeochromocytoma is a neuroendocrine tumour, with an incidence of approximately 0.15 cases per 100 000 per year in the UK.3 The presenting symptoms are sustained or paroxysmal hypertension, sweating, palpitations and anxiety, secondary to excessive production of catecholamines and their metabolites. Diagnosis is based on raised urinary excretion of catecholamines or their metabolites, followed by localisation using CT and/or MRI and specific radio-localisation, usually with meta-iodobenzylguanidine (MIBG).

We present a patient with AIP and fluctuating hypertension in whom the finding of raised catecholamine excretion led to an incorrect diagnosis of co-existent phaeochromocytoma.

A 34-year-old woman, diagnosed with AIP at age 29, developed intermittent labile hypertension which was difficult to control. Urinary catecholamine excretion was found to be abnormal (tables 1 and 2). Abdominal CT and MRI scans were normal but MIBG scintiscan was reported as showing increased …