title: Serum 25-hydroxyvitamin D, parathyroid hormone, calcium intake, and bone mineral density in Spanish adults.
abstract: Vitamin D insufficiency is very common among Spanish community-dwelling adult subjects. A threshold of serum 25(OH)D around 30 ng/ml would be necessary for the prevention of secondary hyperparathyroidism and hip bone loss in our population, regardless of the dairy calcium ingestion.
  
  
  BACKGROUND
  This study aims to assess 25-hydroxyvitamin D-25(OH)D-status in Spanish adult subjects and to analyze its relationships with serum PTH levels, calcium intake, and bone mineral density (BMD).
  
  
  METHODS
  A total of 1811 individuals (1154 postmenopausal women and 657 men) aged 44-93 years participated in the study. Serum 25(OH)D, intact parathyroid hormone (PTH), aminoterminal propeptide of type I collagen (P1NP), and C-terminal telopeptide of type I collagen (β-CTX) levels were measured by electrochemiluminescence. BMD was determined by dual x-ray absorptiometry (DXA) at lumbar spine, femoral neck, and total hip.
  
  
  RESULTS
  Serum 25(OH)D levels were below 10, 20, and 30 ng/ml in 5, 40, and 83 % of participants, respectively. There was a significant seasonal difference in mean serum 25(OH)D, with higher levels in summer-autumn. In multivariate analysis, 25(OH)D levels were negatively correlated with age, serum PTH and creatinine, body mass index, smoking, alcohol intake, and a number of chronic diseases, but positively with dairy calcium intake. The magnitude of the difference in serum PTH according to 25(OH)D quartiles was not influenced by calcium intake. A threshold of serum 25(OH)D around 30 ng/ml was observed for serum PTH and hip BMD.
  
  
  CONCLUSIONS
  Vitamin D insufficiency is very common among Spanish community-dwelling adult subjects. A threshold of serum 25(OH)D around 30 ng/ml would be necessary for the prevention of secondary hyperparathyroidism and hip bone loss in our population, regardless of the dairy calcium ingestion. Programs to improve vitamin D status may be required in our country.
authors.affiliation: Bone Metabolic Unit, Department of Internal Medicine, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008, Santander, Spain. miromj@humv.es.|IDIVAL, Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), University of Cantabria, Santander, Spain. miromj@humv.es.
authors.forename: J M
authors.initials: JM
authors.lastname: Olmos
authors.affiliation: Bone Metabolic Unit, Department of Internal Medicine, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008, Santander, Spain.|IDIVAL, Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), University of Cantabria, Santander, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Hernández
authors.affiliation: Centro de Salud Camargo, Santander, Spain.
authors.forename: P
authors.initials: P
authors.lastname: García-Velasco
authors.affiliation: Bone Metabolic Unit, Department of Internal Medicine, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008, Santander, Spain.|IDIVAL, Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), University of Cantabria, Santander, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Martínez
authors.affiliation: Bone Metabolic Unit, Department of Internal Medicine, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008, Santander, Spain.|Epidemiology Unit, Medical School, University of Cantabria, Centro de Investigación Biomédica en Red Epidemiología y Salud Pública (CIBERESP), Santander, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Llorca
authors.affiliation: Bone Metabolic Unit, Department of Internal Medicine, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008, Santander, Spain.|IDIVAL, Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), University of Cantabria, Santander, Spain.
authors.forename: J
authors.initials: J
authors.lastname: González-Macías
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000187:drug effects / Q000502:physiology*; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D012621:Seasons; D013030:Spain / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25(OH)D; Bone mineral density; Dairy calcium intake; Parathyroid hormone