title: Normohormonal primary hyperparathyroidism is a distinct form of primary hyperparathyroidism.
abstract: Normohormonal primary hyperparathyroidism presents diagnostic and intraoperative challenges, and current literature is conflicting about management. We aim to better define normohormonal primary hyperparathyroidism in order to improve the care for these patients.
  
  
  
  In the study, 516 consecutive patients undergoing parathyroidectomy for primary hyperparathyroidism were divided into 2 groups: classic primary hyperparathyroidism (classic primary hyperparathyroidism, increased serum levels of calcium, and parathyroid hormone) and normohormonal primary hyperparathyroidism (hypercalcemia, normal serum levels of parathyroid hormone). We evaluated inter-group differences in presentation, gland weight, pathology, and complications.
  
  
  
  The normohormonal primary hyperparathyroidism group was comprised of 116 (22.5%) patients. Mean serum levels of parathyroid hormone and calcium were 62.1 pg/mL ± 10.1 and 10.6 mg/dL ± 0.63 in normohormonal primary hyperparathyroidism, and 142 ± 89.0pg/mL and 11.0 ± 0.88 (both P < .01) for classic primary hyperparathyroidism. Nephrolithiasis was more common in normohormonal primary hyperparathyroidism. Multigland hyperplasia was more common in normohormonal primary hyperparathyroidism 23 (19.8%) vs 44 (11%; P = .04). Concordant imaging studies were less likely in normohormonal primary hyperparathyroidism (82 [73.2%] vs 337 [87.1%; P < .01]), had a lesser total gland weight (531.8 mg ± 680.0 vs 1,039.6 mg ± 1,237.3; P < .01), and lesser 2-week parathyroid hormone (32.5 pg/mL ± 18.95 vs 41.0 pg/mL ± 27.8; P = .01). There was no difference in hypoparathyroidism (parathyroid hormone <15 pg/mL; P = .93) at 2 weeks postoperatively.
  
  
  
  Normohormonal primary hyperparathyroidism represents 22.5% of our primary hyperparathyroidism population, which is greater than reported previously. It is a distinct disease process from classic primary hyperparathyroidism in presentation, imaging, and operative findings. More hyperplasia and a lesser gland weight make it challenging to resect the ideal amount of tissue. Studies with long-term follow-up are needed to determine optimal operative management.
authors.affiliation: Department of Surgery, Albany Medical College, Albany, NY. Electronic address: applewm@mail.amc.edu.
authors.forename: Megan K
authors.initials: MK
authors.lastname: Applewhite
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Michael G
authors.initials: MG
authors.lastname: White
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tseng
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Maryam K
authors.initials: MK
authors.lastname: Mohammed
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Frederic
authors.initials: F
authors.lastname: Mercier
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Edwin L
authors.initials: EL
authors.lastname: Kaplan
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Peter
authors.initials: P
authors.lastname: Angelos
authors.affiliation: Department of Endocrinology, University of Chicago, Chicago, IL.
authors.forename: Tamara
authors.initials: T
authors.lastname: Vokes
authors.affiliation: Department of Surgery, Endocrine Surgery Research Program, University of Chicago, Chicago, IL.
authors.forename: Raymon H
authors.initials: RH
authors.lastname: Grogan
mesh_terms: D000328:Adult; D000368:Aged; D002118:Calcium / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy / Q000009:adverse effects / Q000379:methods*; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium