Endocrine Abstracts (2012) 28 N2.1

Primary hyperaldosteronism (Conn's syndrome) and phaeochromocytoma

Khin Swe Myint

Department of Endocrinology, Norfolk and Norwich University Hospital, Norwich, United Kingdom.

Primary hyperaldosteronism (PHA) is increasing common since the use of aldosterone to rein ratio (ARR) as a screening test. It occurs up to 10% patients with hypertension. Indentifying PHA is important as hypertension can either be cured by unilateral adrenalectomy or controlled by targeted medical therapy with mineralocorticoid receptor agonist in bilateral disease. Familiarising with the different assays and unit is crucial on interpreting ARR. Plasma aldosterone concentration (PAC) should be taken into account for indentifying screening positive individuals. Various drugs can interfere with the ARR and careful interpretation is required. High resolution CT could be misleading in patient age <40 year due to increase incidence of incidental adenoma and would not differentiate unilateral to bilateral adrenal hyperplasia. Adrenal venous sampling remains the gold standard test for differentiating unilateral from bilateral disease predicting subsequent response to unilateral adrenalectomy. Pheochromocytoma is a rare chromaffin secreting tumour and diagnosis of which depend on the biochemical evidence of catecholamine secretion by the tumour. With the availability of newer assay of catecholamine metabolites (urinary and plasma metanephrine and normetanephrine), the sensitivity of diagnosis increased but false positive result remains an issue. It is crucial to exclude false positive results due to a con-comitant use of other pharmacotherapy such as paracetamol, tricyclic antidepressant, and betablocker; and in acutely unwell patients such as acute heart failure. More recent report suggested that plasma normetanephrine response following clonidine suppression test was better marker than plasma normetanephrine in diagnosing challenging cases.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.

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