Wed, 09 Jul 2008 16:34:49 BST CiteULike: omalbams chromogranin http://www.citeulike.org/user/omalbam/tag/chromogranin CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/omalbam/article/2216699 <i>J Clin Endocrinol Metab, Vol. 93, No. 1. (1 January 2008), pp. 91-95.</i><br /><br />Context: The initial diagnosis of pheochromocytoma relies on plasma fractionated metanephrines levels. Normal levels exclude pheochromocytoma, but positive tests have a low positive predictive value due to the disease's rarity. Objectives: The objective of the study was to evaluate three approaches to distinguish between true-positive and false-positive tests: 1) increased cutoff for plasma fractionated metanephrines, 2) measurement of serum/plasma chromogranin A (CGA), and 3) urine fractionated metanephrine testing. Design: We studied retrospectively all Mayo Clinic patients with positive plasma fractionated metanephrine tests over a 15-month period and determined their final diagnosis based on histology, imaging, additional biochemical tests, and more than 1 yr follow-up. For a subgroup, urine fractionated metanephrine results were available. All original plasma samples were retested for CGA. Results: Of 140 patients, 40 had a chromaffin tumor confirmed and 100 excluded, indicating a positive predictive value of plasma fractionated metanephrines of 28.6%. Increasing the threshold for a positive test improved specificity to 98% but missed eight cases (20%). Incorporation of urine fractionated metanephrine testing as follow-up test achieved 80% specificity and 91% sensitivity. The corresponding figures for CGA were 71 and 87% for all patients and 89 and 87% when patients taking proton pump inhibitors were excluded. Conclusions: Unless plasma fractionated metanephrines levels are elevated more than 4-fold above the upper limit of normal, patients with a positive plasma fractionated metanephrines test should be evaluated with urine fractionated metanephrines and serum/plasma CGA assays before being subjected to imaging or invasive diagnostic tests. 10.1210/jc.2007-1354 Plasma Chromogranin A or Urine Fractionated Metanephrines Follow-Up Testing Improves the Diagnostic Accuracy of Plasma Fractionated Metanephrines for Pheochromocytoma Alicia Algeciras-Schimnich Carol Preissner William Young Ravinder Singh Stefan Grebe doi:10.1210/jc.2007-1354 J Clin Endocrinol Metab, Vol. 93, No. 1. (1 January 2008), pp. 91-95. 2008-01-10T23:57:34-00:00 2008 J Clin Endocrinol Metab 93 1 91 95 chromogranin diagnosis metanephrines pheochromocytoma