Clinical Endocrinology (2009) 70, 14–17 doi: 10.1111/j.1365-2265.2008.03450.x © 2009 The Authors 14 Journal compilation © 2009 Blackwell Publishing Ltd CLINICAL QUESTION Blackwell Publishing Ltd What are the keys to successful adrenal venous sampling (AVS) in patients with primary aldosteronism? William F. Young* and Anthony W. Stanson† *Divisions of Endocrinology, Diabetes, Metabolism, Nutrition, and Internal Medicine, †the Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA Summary Adrenal venous sampling (AVS) is the criterion standard to distinguish between unilateral and bilateral adrenal disease in patients with primary aldosteronism. The keys to successful AVS include appropriate patient selection, careful patient preparation, focused technical expertise, defined protocol, and accurate data interpretation. The use of AVS should be based on patient preferences, patient age, clinical comorbidities, and the clinical probability of finding an aldosterone-producing adenoma. AVS is optimally performed in the fasting state in the morning. AVS is an intricate procedure because the right adrenal vein is small and may be difficult to locate – the success rate depends on the proficiency of the angiographer. The key factors that determine the successful catheterization of both adrenal veins are experience, dedication and repetition. With experience, and focusing the expertise to 1 or 2 radiologists at a referral centre, the AVS success rate can be as high as 96%. A centre-specific, written protocol is mandatory. The protocol should be developed by an interested group of endocrinologists, radiologists and laboratory personnel. Safeguards should be in place to prevent mislabelling of the blood tubes in the radiology suite and to prevent sample mix-up in the laboratory. (Received 4 September 2008; returned for revision 27 September 2008; finally revised 11 October 2008; accepted 13 October 2008) Introduction Adrenal venous sampling (AVS) is the criterion standard to distin- guish between unilateral and bilateral adrenal disease in patients with primary aldosteronism. 1–3 Although AVS has been in clinical use for more than 45 years, 3,4 the indications for and successful use of AVS continue to be challenging clinical issues. Our objective herein is to answer the question ‘What are the keys to successful AVS in patients with primary aldosteronism?’ The answer to this question is based on our clinical experience and the performance of AVS in more than 400 patients over 18 years at Mayo Clinic. The keys to successful AVS include appropriate patient selection, careful patient preparation, focused technical expertise, defined protocol and accurate data interpretation. Appropriate patient selection Although matching patients to specific tests is important across medicine, it is especially critical in the setting of AVS. For example, although AVS was initially proposed to assist in the localization of catecholamine-secreting neoplasms, 4 with the development of computer-assisted imaging (e.g. computed tomography [CT], magnetic resonance imaging, 123 I-m-iodobenzylguanidine scintigraphy), AVS is now contraindicated in patients with these tumours. 2 Most patients with primary aldosteronism have either bilateral idiopathic hyperplasia (IHA) – optimally treated with mineralocor- ticoid receptor blockade – or a unilateral aldosterone-producing adenoma (APA) that may be treated with unilateral laparoscopic adrenalectomy. 1,5 The use of AVS to distinguish between IHA and APA was first proposed by Melby et al. 1967. 2 However, with the catheter and angiographic technology available at that time, most centres relied on less direct methods to lateralize aldosterone excess as they become available (e.g. [6β- 131 I]iodomethyl-19- norcholesterol [NP-59] scintigraphy, posture stimulation test, serum 18-hydroxycorticosterone concentration, and adrenal CT scan). 5 By the early 1980s, adrenal CT became the localizing procedure of choice. 5 However, multiple studies have shown that the accuracy of adrenal CT in localizing the source of aldosterone excess is poor (approximately 50%) and that in patients with primary aldosteronism who wish to pursue the surgical option for hypertension management, AVS is a key step in distinguishing between unilateral and bilateral adrenal disease. 1,5–13 Some centres and a recent clinical practice guideline recommend that AVS be performed in all patients who have the diagnosis of primary aldosteronism and who want to pursue surgical management. 1,13 A more practical approach is the selective use of AVS on the basis of patient preferences, patient age, clinical comorbidities, and the clinical probability of finding an APA. 5,6,14 AVS should be performed only in patients with confirmed primary aldosteronism Correspondence: William F. Young Jr, Division of Endocrinology, Diabetes, Metabolism, Nutrition, and Internal Medicine, Mayo Clinic Rochester, 200 First Street SW, Rochester, MN 55905, USA. Tel.: +1 507 284 2191; Fax: +1 507 284 5745; E-mail: young.william@mayo.edu