title: Regulation of PTH secretion by 25-hydroxyvitamin D and ionized calcium depends on vitamin D status: a study in a large cohort of healthy subjects.
abstract: BACKGROUND
  Previous papers investigating vitamin D status have often outlined the significant relationships between serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD), but the influence of ionized calcium levels has not been concomitantly considered.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  In 1050 healthy men (547) and women (503), serum ionized calcium (iCa), creatinine (Cr), albumin, 25OHD, and PTH were measured. After conventional analysis, a regression tree was fitted on the data set.
  
  
  RESULTS
  25OHD and PTH values showed significant opposite seasonal changes. 25OHD levels negatively correlated with PTH, which in turn negatively correlated with iCa. A regression tree was fitted to the whole data set using PTH as the response variable and 25OHD and iCa as covariates. PTH concentration depended on that of iCa only in subjects with 25OHD levels>16.35 ng/mL, while for 25OHD<16.35 ng/mL it depended on 25OHD values.
  
  
  CONCLUSIONS
  Our results indicated that PTH levels were highly conditioned by those of 25OHD in subjects with 25OHD values lower than 16.35 ng/mL and by those of iCa only for higher 25OHD concentration.
authors.affiliation: Unit of Internal Medicine, Casa Sollievo della Sofferenza Hospital, I.R.C.C.S., San Giovanni Rotondo (FG), Italy. venz.carnevale@libero.it
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Carnevale
authors.forename: Luciano
authors.initials: L
authors.lastname: Nieddu
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Romagnoli
authors.forename: Claudia
authors.initials: C
authors.lastname: Battista
authors.forename: Maria Lucia
authors.initials: ML
authors.lastname: Mascia
authors.forename: Iacopo
authors.initials: I
authors.lastname: Chiodini
authors.forename: Cristina
authors.initials: C
authors.lastname: Eller-Vainicher
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Frusciante
authors.forename: Stefano Angelo
authors.initials: SA
authors.lastname: Santini
authors.forename: Michele
authors.initials: M
authors.lastname: La Porta
authors.forename: Salvatore
authors.initials: S
authors.lastname: Minisola
authors.forename: Alfredo
authors.initials: A
authors.lastname: Scillitani
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium