1. Neuropeptide Y could replace plasma normetanephrines as a pheochromocytoma screening parameter Ana-Maria Stefanescu*, Sorina Schipor*,Diana Paun*,C.Badiu*,C.Dumitrache* * National Institute of Endocrinology Bucharest-Romania Background Objectives Subjects / Methods Results Discussion Conclusion References stefanescuam@yahoo.com  This prospective case- control study (2010-2014) included a group of 15 hypertensive patients(12 women and 3 men) aged between 33-73years confirmed with pheochromocytoma and an age-matched control group of 15 normotensive subjects without endocrine disfunction  The pheochromocytoma diagnosis was suspected on clinical ground and confirmed by imaging studies and also by plasma neuroendocrine markers  Differentially free plasma NMNp/MNp and plasma NPY were assayed using enzyme- immunoassay for all three markers  The pheochromocytoma group was also evaluated post-surgery for all three endocrine markers  Statistical analysis was performed using Med Calc Software version 8.0.0.1. Windows 98/NT/Me/2000/XP  Expert opinion favors free plasma normetanephrines(NMNp) and metanphrines(MNp) as markers with highest sensitivity for the detection of pheochromocytoma  We considered an opportunity to test plasma NPY besides plasma NMNp/MNp in a selected pheochromocytoma group and to underline the relevance of these parameters for screening studies. 1. Grouzmann E,Gicquel C,Plouin PF,Schlumberger M,Comoy E,Bohuon C.Neuropeptide Y and neuron-specific enolaase levels in benign and malignant pheochromocytomas.Cancer 1990,66(8):1833-5. 2.Januszewicz W,Wocial B,Ignatowska- Switalska H,Dutkiewicz-Ratzkowska M,Feltynowski T,Januszewicz A,Tapińskki M,Zukovska-Grojec Z,Szostek M. Alterations in plasma neuropeptide Y immunoreactivity and catecholamine levels during surgical removal of pheochromocytoma.JHypertens.1998, 16(4):543-7. 3.Eurin J,Barthélemy C,Masson F,Maistre G,Soualmia H,Noé E,Sarfati E,Eurin B,Carayon A.Release of neuropeptide Y and hemodynamic changes during surgical removal of human pheochromocytomas.Regul Pept.2000,86(1-3):95-102  Neuropeptide Y(NPY) is a 36 amino acid peptide distributed throughout the central and peripheral nervous systems including chromaffin cells of the adrenal medulla and is produced in high concentration by pheochromocytomas  A number of studies precised that although only a subset of chromaffin cells express neuropeptide Y(NPY),this peptide was present in a lot of pheochromocytomas and neuroblastomas Cases NMNp pg/mL (mean±SEM) MNp pg/mL (mean±SEM) NPY pg/mL (mean±SEM) 15 pre- surgery 1116.06 ± 301.23 513.46 ± 237.50 1088.02±185.5 15 post- surgery 58.25 ± 6.6434.58 ± 2.5258.25 ± 7.24 15 Normals(n) 46.45 ± 6.3222.62 ± 2.3543.77 ± 6.46 Test t pre vs. n P=0.0011P=0.0412P<0.0001 Test t post vs. n NS Table 1-Values for plasma NMNp,MNp, NPY iin tumoral patients pre vs.post surgery vs.normals Fig1- ROC curves comparison between areas for NPY,NMNp,MNp Table 2- Pairwise comparison of ROC curves NPY NMNp Difference between areas = 0.000 Standard error = 0.000 95% Confidence interval = 0.000 to 0.000 Significance level P = 1.000  In tumor cases all three parameters were increased and normalized after surgery  Values for all 3 markers differed significantly in all tumor cases pre-surgery versus the same markers post-surgery  In tumor patients,plasma values post-surgery are not significantly different versus the same parameters in control group  NPY was present in increased concentration in all 15 tumoral cases and came back in normal limits after surgery  A high correlation coefficient(r=0.79) between NPY and NMNp proved an interdependence between both markers in pheochromocytoma  ROC curves of this both markers didn’t show differences between their areas,so both parameters proved the best sensitivity and specificity(100%) with maximum negative and positive prediction values  Practically,NPY could be a complementary marker in pheochromocytoma or it could be used as a single diagnosis marker instead of NMNp  In our selected pheochromocytoma group,plasma NPY could be used as a diagnosis marker instead of free plasma NMNp with the same sensitivity and specificity  Future studies including an increased number of subjects could confirm the utility of NPY as a screening marker of pheochromocytoma CNMP Funding 42101/2008