title: Role of the oral calcium-loading test with measurement of intact parathyroid hormone in the diagnosis of symptomatic subtle primary hyperparathyroidism.
abstract: BACKGROUND
  This study was designed to assess the diagnostic value of the oral calcium tolerance test with measurement of intact parathyroid hormone by the immunoradiometric assay (IRMA PTH) in the diagnosis of primary hyperparathyroidism in patients with symptoms who have minimal, intermittent, or no elevation of the levels of total calcium and/or intact PTH.
  
  
  METHODS
  After baseline levels of IRMA PTH and total calcium were measured, an oral calcium load of 1000 mg elemental calcium was administered to 10 patients with hyperparathyroidism and 18 normal control subjects. Total calcium and IRMA PTH levels were measured at 30, 60, and 120 minutes after the oral calcium load was administered.
  
  
  RESULTS
  The mean suppression of the baseline level of IRMA PTH in the patients with hyperparathyroidism was 83.7% +/- 6.5% (mean +/- 1 SEM), but the levels of the normal control subjects fell significantly (p < 0.05) lower to 58.8% +/- 3.7% (mean +/- 1 SEM).
  
  
  CONCLUSIONS
  This study suggests that the oral calcium tolerance test may be a valuable adjunct in confirming the diagnosis of primary hyperparathyroidism in patients with symptoms who have minimal, intermittent, or no elevation of the levels of total calcium and/or IRMA PTH:
authors.affiliation: Department of Surgery, Rhode Island Hospital, Providence.
authors.forename: J M
authors.initials: JM
authors.lastname: Monchik
authors.forename: R P
authors.initials: RP
authors.lastname: Lamberton
authors.forename: U
authors.initials: U
authors.lastname: Roth
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D015592:Immunoradiometric Assay; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D011184:Postoperative Period; D012016:Reference Values; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D002118:Calcium