Plasma Chromogranin A or Urine Fractionated Metanephrines Follow-Up Testing Improves the Diagnostic Accuracy of Plasma Fractionated Metanephrines for Pheochromocytoma

@article{citeulike:2216699, abstract = {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}, author = {Algeciras-Schimnich, Alicia and Preissner, Carol M. and Young, William F. and Singh, Ravinder J. and Grebe, Stefan K. }, citeulike-article-id = {2216699}, doi = {10.1210/jc.2007-1354}, journal = {J Clin Endocrinol Metab}, keywords = {chromogranin, diagnosis, metanephrines, pheochromocytoma}, month = {January}, number = {1}, pages = {91--95}, posted-at = {2008-01-11 00:00:30}, priority = {2}, title = {Plasma Chromogranin A or Urine Fractionated Metanephrines Follow-Up Testing Improves the Diagnostic Accuracy of Plasma Fractionated Metanephrines for Pheochromocytoma}, url = {http://dx.doi.org/10.1210/jc.2007-1354}, volume = {93}, year = {2008} }

TY - JOUR ID - citeulike:2216699 L3 - citeulike-article-id:2216699 TI - Plasma Chromogranin A or Urine Fractionated Metanephrines Follow-Up Testing Improves the Diagnostic Accuracy of Plasma Fractionated Metanephrines for Pheochromocytoma JF - J Clin Endocrinol Metab VL - 93 IS - 1 SP - 91 EP - 95 N2 - 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 KW - chromogranin KW - diagnosis KW - metanephrines KW - pheochromocytoma AU - Algeciras-Schimnich, Alicia AU - Preissner, Carol AU - Young, William AU - Singh, Ravinder AU - Grebe, Stefan PY - 2008/01/01/ UR - http://dx.doi.org/10.1210/jc.2007-1354 ER -