title: Different PTH response to oral peptone load and oral calcium load in patients with normocalcemic primary hyperparathyroidism, primary hyperparathyroidism, and healthy subjects.
abstract: BACKGROUND
  Normocalcemic primary hyperparathyroidism (PHPT-N) is a condition that may have similar long-term implications to primary hyperparathyroidism (PHPT); however, differential diagnosis and treatment for parathyroid disorders are not clearly defined. We investigated the effect of an oral peptone and an oral calcium load on calcium-regulating hormones in PHPT-N compared with PHPT and healthy controls to provide a new potential diagnostic tool.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  We evaluated serum gastrin, PTH, ionized calcium, and phosphate responses to oral calcium (1 g) and peptone (10 g) load in 22 PHPT and 20 PHPT-N patients matched for PTH serum values. Moreover, 30 healthy subjects were enrolled as controls. In 12 patients for each group, we also performed the oral peptone test adding aluminum hydroxide (AH) to suppress phosphate absorption.
  
  
  RESULTS
  In PHPT patients, PTH increased significantly 30 min after the oral peptone load, while no significant increase was found in PHPT-N and controls. After oral calcium load, PTH remained stable in PHPT while it decreased dramatically in PHPT-N patients, and ionized calcium increased significantly in each of the three groups. Peptones plus AH induced a blunted PTH increase in the three groups.
  
  
  CONCLUSIONS
  Considering the marked difference in PTH response elicited by peptones in PHPT compared with PHPT-N, we suggest that the oral peptone test could be added to the diagnostic evaluation of PHPT patients. In case of absent response to peptones, patients should have their serum calcium levels assessed twice a year in accordance with recent guidelines.
authors.affiliation: Physical and Rehabilitation Medicine, Department of Health Sciences, University of Eastern Piedmont A. Avogadro, AOU Maggiore della Carità, Viale Piazza D'armi 1, 28100 Novara, Italy. marco.invernizzi@med.unipmn.it
authors.forename: Marco
authors.initials: M
authors.lastname: Invernizzi
authors.forename: Stefano
authors.initials: S
authors.lastname: Carda
authors.forename: Velella
authors.initials: V
authors.lastname: Righini
authors.forename: Alessio
authors.initials: A
authors.lastname: Baricich
authors.forename: Carlo
authors.initials: C
authors.lastname: Cisari
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bevilacqua
mesh_terms: D000284:Administration, Oral; D000368:Aged; D002118:Calcium / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D003937:Diagnosis, Differential; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D004305:Dose-Response Relationship, Drug; D005260:Female; D006262:Health; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000032:analysis / Q000097:blood*; D010461:Peptones / Q000008:administration & dosage / Q000494:pharmacology*; D012016:Reference Values
chemical_list: D010281:Parathyroid Hormone; D010461:Peptones; D002118:Calcium