Endocrine Abstracts (2015) 38 OC2.2 | DOI: 10.1530/endoabs.38.OC2.2

Adrenal vein catecholamine levels and ratios: reference intervals derived from patients with primary aldosteronism

Sam O’Toole1, Candy Sze1, Kent Tirador1, Scott Akker1, Matthew Matson2, Les Perry3, Maralyn Druce1, Tanja Dekkers4, Jaap Deinum4, Jacques Lenders4, Graeme Eisenhofer5,6 & William Drake1

1Department of Endocrinology, St Bartholomew’s Hospital, London, UK; 2Department of Radiology, St Bartholomew’s Hospital, London, UK; 3Department of Biochemistry, St Bartholomew’s Hospital, London, UK; 4Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands; 5Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; 6Department of Internal Medicine III, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.

Introduction: Phaeochromocytoma localisation is generally reliably achieved with modern imaging techniques, particularly in sporadic cases. Diagnostic doubt can arise due to the presence of bilateral adrenal abnormalities, particularly in patients with mutations in genes predisposing them to the phaeochromocytoma development. In such cases, surgical intervention is ideally limited to large or functional lesions due to the long-term consequences associated with hypoadrenalism. Adrenal venous sampling (AVS) for catecholamines has been used in this situation to guide surgery, although there is little data available to support diagnostic cut offs.

Methods: 172 consecutive patients underwent AVS for localisation of established primary aldosteronism (PA) at two centres (St Bartholomew’s Hospital, London and Radboud University Medical Center, Nijmegen) with measurement of adrenal and peripheral venous catecholamines in addition to cortisol and aldosterone. Data from six additional patients with phaeochromocytomas who underwent AVS for diagnostic purposes with subsequent histological confirmation is included.

Results: In the PA cohort, total adrenaline (A; 61.4+2.5 nmol/l vs 35.1+5.1) and noradrenaline (NA; 16.3+2.47 nmol/l vs 2.47 nmol/l) were higher in the right adrenal vein than in the left (P<0.05). This gradient was reversed when the NA:A ratio was considered (right: 0.26+0.04; left: 0.40+0.03; P<0.05). Reference intervals for adrenal venous NA:A were constructed; the ratio for the 97.5th centile was 1.2 on the left and 1.02 on the right. Six patients with phaeochromocytomas underwent AVS for diagnostic purposes with subsequent histological confirmation. Using the 97.5th centile from the PA population, the false negative rate in the phaeochromocytoma group was 0%.

Discussion: This study describes the largest dataset of adrenal venous catecholamine measurements and provides reference intervals in patients without pheochromocytoma. This strengthens the certainty with which conclusions related to AVS for catecholamines can be drawn, acknowledging the procedure is not part of the routine diagnostic work-up and is an adjunct for use only in difficult clinical cases.