title: Weight difference between double parathyroid adenomas is the cause of false-positive IOPTH test after resection of the first lesion.
abstract: BACKGROUND
  Some patients with double parathyroid adenoma show a greater than 50% decline in intraoperative parathyroid hormone (IOPTH) after resection of the first lesion. The present study was designed to test the hypothesis that significant adenoma weight differences may explain this inappropriate decline of IOPTH.
  
  
  METHODS
  We reviewed prospective database records at two tertiary institutions. Patients with a histopathologic diagnosis of double adenoma and no familial history of hyperparathyroidism were included. Diagnosis of double adenoma was confirmed either preoperatively (double uptake), intraoperatively (bilateral exploration), or at reintervention. IOPTH was determined following the Miami protocol. The 10-min postexcision sample was considered as the 0-min sample for IOPTH determinations at the time of resection of the second lesion.
  
  
  RESULTS
  Thirteen patients met the inclusion criteria. After resection of the first lesion, IOPTH failed to decline in four patients and a second adenoma was removed. They had similar weight (404 vs. 598 mg). In nine patients IOPTH showed a false greater than 50% decline. These patients had the largest adenoma removed first (846 +/- 226 mg), and only two had normal PTH serum concentrations 10 min after resection. The second adenoma was always smaller (284 +/- 177 mg; P = 0.02) and its resection either during the same operation (7 cases) or at reoperation (2 cases) led to normalization of IOPTH at 10 min in all cases.
  
  
  CONCLUSIONS
  Two-thirds of patients with double parathyroid adenoma show a false-positive decline of IOPTH after resection of the first adenoma. This appears to be due to the initial removal of the larger lesion.
authors.affiliation: Endocrine Surgery Unit, Hospital del Mar, Barcelona, Spain. asitges@imas.imim.es
authors.forename: Antonio
authors.initials: A
authors.lastname: Sitges-Serra
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Díaz-Aguirregoitia
authors.forename: Aitor
authors.initials: A
authors.lastname: de la Quintana
authors.forename: Jesús
authors.initials: J
authors.lastname: Gil-Sánchez
authors.forename: Jaime
authors.initials: J
authors.lastname: Jimeno
authors.forename: Rosa
authors.initials: R
authors.lastname: Prieto
authors.forename: Joan J
authors.initials: JJ
authors.lastname: Sancho
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D000328:Adult; D000368:Aged; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010282:Parathyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D011446:Prospective Studies; D011877:Radionuclide Imaging; D018709:Statistics, Nonparametric
chemical_list: D010281:Parathyroid Hormone