Endocrine Abstracts

Pheochromocytomas are neuroendocrine tumors able to synthesise cathecholamines as well as to metabolise them in metanephrines (NM,M). We assayed Adrenaline, NorAdrenaline, Dopamine and metanephrines in serum (p) and urine (u), and the chromogranin A. We measured 11 parameters (Ap, Au, NAp, NAu, Du, MNp, MNu, Mp, Mp, 3Metu, CgA). Catecholamines and metanephrines were performed using HPLC with electrochemical detection, and CgA with an immunometric assay. The aim of this study was to evaluate each parameter, to adapt the cut-off levels for diagnosis as well as to evaluate the contribution of the CgA. We studied two groups of patients: group1 consisted of 63 patients with proven pheochromocytomas. They included 49 pheochromocytomas and 14 paragangliomas. Fourteen patients had genetic pathology (22%) (2 NEM2, 5 VHL, 3 SDHB, 2 SDHC, 2 SDHD). The control group included 71 patients. The control group had false positive results for all the serum assays (between. 6 and 24% for NMp). We searched the best sensitivity and specificity with ROC curves. The three best tests were NMu, NMp and CgA with areas under curves respectively to 0.992, 0.990 and 0.988. We then raised the cut-off levels for those parameters for decrease the false positive results. The other parameters were Du<Au<Ap<Mp<Mu<3Met<Nap<NAu. The areas under curves ranged from 0.689 (Du) to 0.946 (NAu). A significant difference was found between sporadic and hereditary diseases only for Ap (P=0.03), Au (P<0.01), Mp (0.015), Mu (P=0.01). The adrenaline pathway seemed to be less often active in hereditary pheochromocytomas. In conclusion, it’s important to refine the cut-off levels for these diagnostic tests to ensure they are adequately sensitive. We have confirmed that the sensitivity and specificity of NM, M and 3Met are relatively better than NA, A and D assays. Urinary tests were more specific for detecting sporadic diseases and NMp, Mp were more sensitive for familial diseases. We have also show that CgA is a useful test which increased the sensitivity of the metanephrines assays.