title: Estimation of the 25(OH) vitamin D threshold below which secondary hyperparathyroidism may occur among African migrant women in Paris.
abstract: OBJECTIVE
  It has previously been shown that there is a threshold of serum 25-hydroxy vitamin D below which secondary hyperparathyroidism may occur. Our purpose was to estimate this threshold in a population of migrant African women living in Paris.
  
  
  METHODS
  Between February 2008 and December 2009, measurements of 25-hydroxy vitamin D and parathormone were performed in 165 African migrant women living in Paris. The estimation of 25-hydroxy vitamin D and parathormone marginal distributions as Gaussian mixtures, combined with a nonparametric kernel estimation method of the regression function of parathormone on 25-hydroxy vitamin D, provided the desired estimate of serum 25-hydroxy vitamin D threshold.
  
  
  RESULTS
  In our sample of African women, our method has shown that serum 25-hydroxy vitamin D levels below 48 ± 2 nmol/L may induce an increase in parathormone concentrations.
  
  
  CONCLUSIONS
  In this sample, our method provided a reliable estimate (95 % confidence interval) of the serum 25-hydroxy vitamin D level below which an increase in parathormone concentrations can be observed.
authors.affiliation: Community Clinic, Paris, France. eemilion@gmail.com
authors.forename: Ernest
authors.initials: E
authors.lastname: Emilion
authors.forename: Richard
authors.initials: R
authors.lastname: Emilion
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000328:Adult; D000349:Africa / Q000208:ethnology; D002112:Calcifediol / Q000097:blood*; D004032:Diet / Q000009:adverse effects / Q000208:ethnology; D054242:Emigrants and Immigrants; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood* / Q000208:ethnology / Q000209:etiology; D008875:Middle Aged; D016011:Normal Distribution; D010281:Parathyroid Hormone / Q000097:blood; D010297:Paris / Q000453:epidemiology; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014808:Vitamin D Deficiency / Q000208:ethnology / Q000503:physiopathology*
chemical_list: C470125:PTH protein, human; D010281:Parathyroid Hormone; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol