ORIGINAL ARTICLE NP-59 test for preoperative localization of primary hyperaldosteronism Marcello Di Martino 1 & Iñigo García Sanz 1 & Jose Luis Muñoz de Nova 1 & Cristina Marín Campos 1 & Miguel Martínez Martín 1 & Luis Domínguez Gadea 1 Received: 23 November 2016 /Accepted: 31 January 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Purpose Adrenal venous sampling is generally considered the gold standard to identify unilateral hormone production in cases of primary hyperaldosteronism. The aim of this study is to eval- uate whether the iodine-131-6-β-iodomethyl-19-norcholesterol (NP-59) test may represent an alternative in selected cases. Methods Patients submitted to laparoscopic adrenalectomy for suspected primary hyperaldosteronism (n = 27) were ret- rospectively reviewed. When nuclear medicine tests were pre- operatively performed, their results were compared with the histopathologic findings and clinical improvement. Results Nuclear medicine tests were realized in 13 patients. In 11 (84.6%), a planar anterior and posterior NP-59 scintigraphy was performed and a SPECT/TC in two (15.4%). Scintigraphy indicated a preoperative lateralization in 12 out of 13 patients (92.3%). When the value of NP-59 tests was based on pathologic results, it showed a sensitivity of 90.9% and a positive predictive value of 83.3%. When the nuclear medicine test’ s performance was based on postoperative blood pressure control, both sensitivity and positive predictive value were 91.6%. Conclusions Nuclear medicine tests represent a useful tool in the preoperative localisation of primary hyperaldosteronism with a high sensitivity and positive predictive value. In pa- tients with contraindications to adrenal venous sampling like contrast allergies, or when it is inconclusive, scintigraphy can represent a useful and non-invasive alternative. Keywords Primary hyperaldosteronism . Adrenal adenoma . NP-59 scintigraphy . NP-59 SPECT/TC Abbreviations NP-59 Iodine-131-6-β-iodomethyl-19-norcholesterol PA Primary hyperaldosteronism IAH Idiopathic bilateral adrenal hyperplasia UAH Unilateral adrenal hyperplasia CT Computed tomography MRI Magnetic resonance imaging AVS Adrenal Venous Sampling PPV Positive predictive value ARR Aldosterone-to-renin ratio NM Nuclear medicine SPECT-CT Single-photon emission computed tomography BP Blood pressure TP True positive FN False negative FP False positive NH Nodular hyperplasia SUV max Maximum standarized uptake values Introduction The prevalence of primary hyperaldosteronism (PA) among hypertensive patients is reported to range from 1 to 20% [1]. In 30–40% of PA, the hormone hyperproduction is attributable to a unilateral aldosterone-producing adenoma (APA). The oth- er frequent cause is idiopathic bilateral adrenal hyperplasia (IAH), while familiar syndromes, adrenocortical carcinoma and unilateral adrenal hyperplasia (UAH) represent other less frequent aetiologies [2, 3]. Laparoscopic adrenalectomy is the treatment of choice when the increased production of * Marcello Di Martino marcellodima@gmail.com 1 University Hospital La Princesa, Madrid, Spain Langenbecks Arch Surg DOI 10.1007/s00423-017-1561-1