title: Factors influencing pre-operative urinary calcium excretion in primary hyperparathyroidism.
abstract: OBJECTIVE
  Normal or elevated 24-hour urinary calcium (Ca) excretion is a diagnostic marker in primary hyperparathyroidism (PHPT). It is used to distinguish familial hypocalciuric hypercalcaemia (FHH) from PHPT by calculating the Ca/creatinine clearance ratio (CCCR). The variance of CCCR in patients with PHPT is considerable. The aim of this study was to analyse the parameters affecting CCCR in patients with PHPT.
  
  
  METHODS
  The data were collected prospectively. Patients with sporadic PHPT undergoing successful surgery were included in a retrospective analysis.
  
  
  METHODS
  The analysis covered 381 patients with pre-operative workup 2 days before removal of a solitary parathyroid adenoma.
  
  
  METHODS
  The impact of serum Ca and 25-hydroxyvitamin D3 (25-OH D3) on CCCR.
  
  
  RESULTS
  The coefficient of determination (R2) in the multivariable model for CCCR consisting of age, Ca, 25-OH D3, 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3), testosterone (separately for males and females), intact parathyroid hormone (iPTH) and osteocalcin was 25.8%. The only significant parameters in the multivariable analysis were 1,25-(OH)2 D3 and osteocalcin with a drop in R2of 15.4% (P<.001) and 2.4% (P=.006), respectively. Bone mineral densities at the lumbar spine, distal radius and left femoral neck were not associated with CCCR (r=-.08, r=-.10 and r=-0.09).
  
  
  CONCLUSIONS
  In multivariable analysis, 1,25-(OH)2 D3 and osteocalcin were the only factors correlating with CCCR. Vitamin D3 replacement may therefore impair the diagnostic value of CCCR and increase the importance of close monitoring of urinary Ca excretion during treatment.
authors.affiliation: Section of Endocrine Surgery, Division of General Surgery, Department of Surgery, Medical University of Vienna, Wien, Austria.|Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
authors.forename: Reto M
authors.identifier: http://orcid.org/0000-0001-8190-8771
authors.initials: RM
authors.lastname: Kaderli
authors.affiliation: Section of Endocrine Surgery, Division of General Surgery, Department of Surgery, Medical University of Vienna, Wien, Austria.
authors.forename: Philipp
authors.initials: P
authors.lastname: Riss
authors.affiliation: Section for Clinical Biometrics, Centre for Medical Statistics, Informatics and Intelligent Systems (CeMSIIS), Medical University of Vienna, Wien, Austria.
authors.forename: Angelika
authors.initials: A
authors.lastname: Geroldinger
authors.affiliation: Section of Endocrine Surgery, Division of General Surgery, Department of Surgery, Medical University of Vienna, Wien, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Selberherr
authors.affiliation: Section of Endocrine Surgery, Division of General Surgery, Department of Surgery, Medical University of Vienna, Wien, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Scheuba
authors.affiliation: Section of Endocrine Surgery, Division of General Surgery, Department of Surgery, Medical University of Vienna, Wien, Austria.
authors.forename: Bruno
authors.initials: B
authors.lastname: Niederle
mesh_terms: D000368:Aged; D002118:Calcium / Q000652:urine*; D003404:Creatinine / Q000652:urine; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000151:congenital / Q000175:diagnosis; D049950:Hyperparathyroidism, Primary / Q000175:diagnosis* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010282:Parathyroid Neoplasms / Q000601:surgery; D057234:Preoperative Period; D012189:Retrospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: C118756:dihydroxy-vitamin D3; D015675:Osteocalcin; D014807:Vitamin D; D003404:Creatinine; D002118:Calcium
keywords: influencing factors; primary hyperparathyroidism; urinary calcium excretion; vitamin D