title: Dietary calcium intake influences the relationship between serum 25-hydroxyvitamin D3 (25OHD) concentration and parathyroid hormone (PTH) concentration.
abstract: OBJECTIVE
  To investigate whether dietary calcium intake will modify the relationship between serum 25-hydroxyvitamin D3 (25OHD) with intact serum parathyroid hormone (PTH) concentrations in apparently healthy Indian adolescents.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Apparently healthy adolescents aged 10-14 years (n=181), from Gujarat, western India. Study conducted from January 2012 to March 2014.
  
  
  METHODS
  Serum 25OHD concentrations and intact serum PTH concentrations (both using chemiluminescent microparticle immunoassay) were measured. Diet was recorded through 24 h diet recall and calcium intake was computed (C-diet V.2.1). To assess relationship between 25OHD and PTH, data were dichotomised according to median calcium intakes (520 mg/day) and relationship between serum 25OHD and PTH in the two subgroups was plotted.
  
  
  RESULTS
  Subjects with calcium intakes above median (>520 mg/day) had lower intact serum PTH values for given serum 25OHD concentration while those with calcium intakes below median (<520 mg/day) had higher intact serum PTH values for given serum 25OHD concentration. Serum 25OHD concentration was negatively correlated with intact serum PTH concentration at lower as well as higher calcium intakes (r=- 0.606 and -0.483, respectively, p<0.01 for both). Using a regression analysis, predicted values for intact serum PTH concentration for the given serum 25OHD concentrations were plotted. The plot revealed a negative shift with increasing calcium intake.
  
  
  CONCLUSIONS
  Dietary calcium intake modifies the relationship between serum 25OHD concentrations and intact serum PTH concentrations. Thus, dietary calcium intake should be taken into account when assessing an individual's vitamin D status.
authors.affiliation: Department of Biotechnology, Hemchandracharya North Gujarat University, Patan, Gujarat, India.
authors.forename: Prerna
authors.initials: P
authors.lastname: Patel
authors.affiliation: Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester, UK.
authors.forename: M Zulf
authors.initials: MZ
authors.lastname: Mughal
authors.affiliation: Department of Biotechnology, Hemchandracharya North Gujarat University, Patan, Gujarat, India.
authors.forename: Pinal
authors.initials: P
authors.lastname: Patel
authors.affiliation: Department of Biochemistry, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: Bhrugu
authors.initials: B
authors.lastname: Yagnik
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Kajale
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Rubina
authors.initials: R
authors.lastname: Mandlik
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Vaman
authors.initials: V
authors.lastname: Khadilkar
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Shashi A
authors.initials: SA
authors.lastname: Chiplonkar
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Supriya
authors.initials: S
authors.lastname: Phanse
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Vivek
authors.initials: V
authors.lastname: Patwardhan
authors.affiliation: Department of Biotechnology, Hemchandracharya North Gujarat University, Patan, Gujarat, India.
authors.forename: Ashish
authors.initials: A
authors.lastname: Patel
authors.affiliation: Hirabai Cowasji Jehangir Medical Research Institute, Jehangir Hospital, Pune, Maharashtra, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Khadilkar
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D002112:Calcifediol / Q000097:blood*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002648:Child; D003430:Cross-Sectional Studies; D004032:Diet; D015930:Diet Records; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D012044:Regression Analysis
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D002112:Calcifediol
keywords: Adolescent Health; Calcium; Parathyroid Hormone; Vitamin D