Introduction: Measurement of plasma metanephrines (PMETS) is widely regarded as one of the best screening tests for phaeochromocytoma/paraganglioma (P/PGL). Current Endocrine Society guidelines recommend that samples for PMETS are ideally collected in the supine position after 30 min rest and interpreted using supine reference ranges, in order to optimise the diagnostic performance of the test. Current practice in our centre is to collect samples for PMETS from seated patients.
Aim: To determine if seated sampling for PMETS provides acceptable diagnostic performance in our centre.
Methods: Clinical and laboratory data of 113 patients were reviewed, gathered over a 4-year period 20102014. All had undergone preoperative PMETS measurement (LC-MS/MS) and all had post-operative pathology confirmation or exclusion of P/PGL.
Results: Of the113 patients included in the study, 40 had a histological diagnosis of P/PGL. Of these 40, three were considered pre and peri-operatively to be non-secretory. The remaining 73 patients had an alternative adrenal pathology. The diagnostic sensitivity of PMETS (either normetanephrine or metanephrine) above the upper limit of our in-house seated reference range was 93%. However, excluding three cases of PGL determined clinically and biochemically to be non-secretory raised the sensitivity to 100%. Diagnostic specificity was 91%. Applying published supine reference ranges made no difference to diagnostic sensitivity in this group of patients, but decreased diagnostic specificity to 77%.
Conclusions: While these data are derived from a relatively small study population, they demonstrate acceptable diagnostic performance for seated PMETS as a screening test for P/PGL. The data highlight a high diagnostic sensitivity for PMETS with seated sampling in our centre.