title: Performance of plasma fractionated free metanephrines by enzyme immunoassay in the diagnosis of pheochromocytoma and paraganglioma.
abstract: OBJECTIVE
  To study the performance of measuring plasma fractionated free metanephrines by enzyme immunoassay (EIA) in the diagnosis of pheochromocytoma and catecholamine-secreting paraganglioma.
  
  
  METHODS
  Consecutive patients attending the endocrine clinic at King Edward Memorial Hospital, Mumbai, India, for suspicion of catecholamine-secreting tumors were included. Plasma fractionated free metanephrines were measured by EIA, and computed tomography of the neck, chest, abdomen, and pelvis was performed. Those with tumor identified by imaging underwent 131I m-iodobenzylguanidine scintigraphy. All patients with adrenal masses larger than 3 cm and patients with secretory tumors, irrespective of their size, underwent tumor excision. The rest were followed up for 6 to 12 months.
  
  
  RESULTS
  One hundred patients with a clinical suspicion of pheochromocytoma or paraganglioma were included. Plasma free normetanephrine alone had a sensitivity of 94.1% (cutoff: 180 ng/mL), while plasma free metanephrine had a sensitivity of 14.7% (cutoff: 90 pg/mL). Both had 96.9% specificity. When combined (either test positive), the sensitivity was 94.1% with a specificity of 93.75%. Thirty-four patients had a histopathologically proven pheochromocytoma or paraganglioma. It was concluded that 66 patients did not harbor a pheochromocytoma or catecholamine-secreting paraganglioma.
  
  
  CONCLUSIONS
  Plasma fractionated free metanephrines measured by EIA have good sensitivity and specificity in the diagnosis of pheochromocytoma and catecholamine-secreting paraganglioma.
authors: Department of Endocrinology, Seth GS Medical College, Mumbai, India. drvijayasarathi@gmail.com
authors: Vijaya
authors: V
authors: Sarathi
authors: Reshma
authors: R
authors: Pandit
authors: Varsha
authors: V
authors: Jagtap
authors: Anurag R
authors: AR
authors: Lila
authors: Tushar R
authors: TR
authors: Bandgar
authors: Padma S
authors: PS
authors: Menon
authors: Prema
authors: P
authors: Varthakavi
authors: Vijaya P
authors: VP
authors: Raghavan
authors: Nalini S
authors: NS
authors: Shah
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D008676:Metanephrine / Q000097:blood*; D010235:Paraganglioma / Q000097:blood / Q000175:diagnosis*; D010673:Pheochromocytoma / Q000097:blood / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D008676:Metanephrine