title: A new, vitamin D-based, multidimensional nomogram for the diagnosis of primary hyperparathyroidism.
abstract: OBJECTIVE
  To refine the diagnostic criteria for primary hyperparathyroidism (1°HPT) to identify atypical patients, in whom serum calcium, parathyroid hormone (PTH), or both are within the "normal" range.
  
  
  METHODS
  Total serum calcium, intact PTH, and 25-hydroxyvitamin D [25(OH)D] levels were measured in patients with 1°HPT and healthy patient groups. Multivariate analysis of healthy patient data first identified factors that significantly affected PTH levels and defined a new PTH reference range with a mathematical model. That nomogram was then validated for prediction of atypical 1°HPT in patients with surgically confirmed disease.
  
  
  RESULTS
  On multivariate analysis, calcium (P = .0002), 25(OH)D (P<.0001), and age (P = .015) independently affected PTH. With these variables, we created a 4-dimensional nomogram that distinguished normal patients from those with hyperparathyroid states. Mathematically, this nomogram predicts 1°HPT when the measured serum PTH value is higher than PTH calculated by the following formula: PTH (pg/mL) = 120 - [6 × calcium (mg/dL)] - [0.52 × 25(OH)D (ng/mL)] + [0.26 × patient age (years)]. When applied to our surgical group of patients, this nomogram successfully identified 100% of patients (238 of 238) with classic 1°HPT, 84% (64 of 76) with normocalcemic 1°HPT, and 54% (20 of 37) with 1°HPT and normal PTH.
  
  
  CONCLUSIONS
  This study uniquely defines a patient-specific upper limit of normal for PTH based on the readily available variables of serum calcium, 25(OH)D, and patient age. Our nomogram may allow for more rapid definitive diagnosis and treatment of 1°HPT in patients with atypical presentations.
authors: Department of Endocrine Surgery, University of Calgary, Alberta, Canada.
authors: Adrian
authors: A
authors: Harvey
authors: MengJun
authors: M
authors: Hu
authors: Manjula
authors: M
authors: Gupta
authors: Robert
authors: R
authors: Butler
authors: Jamie
authors: J
authors: Mitchell
authors: Eren
authors: E
authors: Berber
authors: Allan
authors: A
authors: Siperstein
authors: Mira
authors: M
authors: Milas
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D000328:Adult; D000367:Age Factors; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000097:blood*; D015331:Cohort Studies; D003949:Diagnostic Techniques, Surgical; D005260:Female; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015999:Multivariate Analysis; D049451:Nomograms; D009820:Ohio; D010281:Parathyroid Hormone / Q000097:blood*; D012189:Retrospective Studies
chemical_list: C470125:PTH protein, human; D010281:Parathyroid Hormone; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol; D002118:Calcium