title: Association of Parathyroid Gland Biopsy Excision Technique With Ex Vivo Radiation Counts During Radioguided Parathyroid Surgery.
abstract: Parathyroid biopsy represents a means for normal and hyperfunctional glands to be distinguished intraoperatively. However, no data exist to guide surgeons regarding how much of a parathyroid gland must be biopsied to satisfy the 20% rule.
  
  
  
  To quantify the relative proportion of a hyperfunctional parathyroid gland that must be evaluated with the gamma probe to satisfy the 20% rule.
  
  
  
  A retrospective review of surgical data for 24 consecutive patients (16 women, 18 men; mean [SD] age, 66.6 [10] years; range, 51-83 years) who underwent surgery for primary hyperparathyroidism between May and October, 2015, in a tertieary academic medical center.
  
  
  
  Extirpated parathyroid glands were sectioned into parallel or pie-shaped biopsies and evaluated ex vivo with a gamma probe to determine what percentage of a hyperfunctional gland must be sampled to meet the Norman 20% rule. The hypothesis was formulated during data collection.
  
  
  
  In total, 253 ex vivo biopsy specimens were obtained from 33 surgically removed parathyroid glands. Parathyroid biopsies satisfied the 20% rule with an accuracy that depended on the relative proportion of the parent gland represented: half or more (96.6%; 95% CI, 91.7%-100.0%), a quarter to one-half (87.0%; 95% CI, 79.3%-94.7%), less than a quarter (63.6%; 95% CI, 54.5%-72.8%). When less than a quarter of the gland was removed, pie-shaped biopsies were more likely to satisfy the 20% rule compared with parallel biopsies of the same weight (78.4% vs 56.2%; absolute difference, 22.2%; 95% CI, 4.7%-39.7%).
  
  
  
  Unless half of a parathyroid gland is biopsied during radioguided parathyroidectomy, the 20% rule cannot reliably rule out the presence of a hyperfunctional parathyroid lesion. Pie-shaped biopsies originating from the center of the gland are associated with a lower rate of false-negative results compared with peripheral biopsies of similar size. Pie-shaped biopsies and biopsy of half or more of each nonexcised parathyroid gland for ex vivo counts may increase the risk of remnant devascularization and resultant hypoparathyroidism.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Hinson
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock2Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Lawson
authors.affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock.
authors.forename: Aime T
authors.initials: AT
authors.lastname: Franco
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock.
authors.forename: Brendan C
authors.initials: BC
authors.lastname: Stack
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods*; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016105:Parathyroidectomy / Q000379:methods*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D017256:Technetium Tc 99m Sestamibi
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi