title: Vitamin D status and secondary hyperparathyroidism: the importance of 25-hydroxyvitamin D cut-off levels.
abstract: BACKGROUND
  Serum 25-hydroxyvitamin D is the best indicator of vitamin D status. However, some controversy remains regarding "normal" and "abnormal" values. This study's aim was to assess vitamin D status and prevalence of secondary hyperparathyroidism.
  
  
  METHODS
  A random sample of 326 subjects (164 women and 162 men, aged 68 +/- 9; range, 54 to 89) participating in the European Vertebral Osteoporosis Study (EVOS) was used to assess vitamin D status and secondary hyperparathyroidism. Only those subjects who had never received any kind of treatment for osteoporosis were included in this analysis.
  
  
  RESULTS
  Serum 25-hydroxyvitamin D levels were "deficient" (<10 ng/mL) in 27% of subjects, "borderline" (10-18 ng/mL) in 40% of subjects, and "normal" (>18 ng/mL) in 33% of subjects. The prevalence of secondary hyperparathyroidism (PTH>65 pg/mL) according to 25-hydroxyvitamin D levels was 33% (<10 ng/mL), 16% (10-18 ng/mL), and 12% (>18 ng/mL), respectively. There were no cases of secondary hyperparathyroidism with 25-hydroxyvitamin D levels>40 ng/mL. The independent predictors for PTH were 25-hydroxyvitamin D and serum creatinine in both sexes, but age was a predictor only in men.
  
  
  CONCLUSIONS
  These remarkable findings demonstrate the importance of maintaining higher 25-hydroxyvitamin D levels to avoid stimulation of the parathyroid gland.
authors.affiliation: Bone and Mineral Research Unit, Instituto Reina Sofía de Investigación, Hospital Central de Asturias, Universidad de Oviedo, Spain. cgomez@hca.es
authors.forename: Carlos
authors.initials: C
authors.lastname: Gómez-Alonso
authors.forename: Manuel L
authors.initials: ML
authors.lastname: Naves-Díaz
authors.forename: Jose L
authors.initials: JL
authors.lastname: Fernández-Martín
authors.forename: Jose B
authors.initials: JB
authors.lastname: Díaz-López
authors.forename: Maria T
authors.initials: MT
authors.lastname: Fernández-Coto
authors.forename: Jorge B
authors.initials: JB
authors.lastname: Cannata-Andía
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D013030:Spain / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D