title: Determinants of circulating 25-hydroxyvitamin D and bone mineral density in young physicians.
abstract: OBJECTIVE
  To examine determinants of serum 25-hydroxyvitamin D [25(OH)D] and bone mineral density (BMD) in young physicians, a group not well studied previously.
  
  
  METHODS
  We analyzed data from a questionnaire completed by young physicians as well as results of serum 25(OH)D, serum parathyroid hormone, and BMD measurements.
  
  
  RESULTS
  Among 104 study subjects, 42% were white, 46% were Asian, 12% were "other" (10 Hispanic and 2 African American subjects), and 75% were women. The mean age and body mass index (BMI) were 28.1 years and 23.0 kg/m², respectively. White subjects had a higher mean serum 25(OH)D level (27.3 ng/mL) than did Asian subjects (15.9 ng/mL) and other subjects (22.3 ng/mL) (P<.0001). White subjects tended to have higher Z-scores than Asian subjects and other subjects for the hip (P = .06), trochanter (P = .08), and lumbar spine (P = .08). The serum 25(OH)D level was negatively associated with serum parathyroid hormone (r = -0.44; P<.01) but not with BMD. The prevalence of vitamin D insufficiency [serum 25(OH)D <30 ng/mL, 77% for the entire group] was higher (P<.01) in Asian subjects (93%) than in white subjects (61%) and other subjects (73%). Significant determinants of serum 25(OH)D included age, ethnicity, exposure to sunlight, use of vitamin D supplements, and family history of osteoporosis (P<.05 for all), and together with sex, calcium supplements, exercise, and BMI, these factors explained 49% of serum 25(OH)D level variability. Significant determinants of low BMD (osteopenia plus osteoporosis, prevalence 37.5%) included sex (P = .002) and BMI (P<.0001) but not serum 25(OH)D; Asian ethnicity reached borderline significance (P = .088). Age, sex, ethnicity, smoking, and BMI explained 20% to 30% of the Z-score variations.
  
  
  CONCLUSIONS
  In young physicians with a healthful lifestyle, determinants of low serum 25(OH)D and BMD included modifiable risk factors. Vitamin D insufficiency and low BMD could be important contributors to future osteoporotic fractures in this population.
authors.affiliation: Section of Endocrinology, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
authors.forename: Buvana
authors.initials: B
authors.lastname: Manickam
authors.forename: Terri
authors.initials: T
authors.lastname: Washington
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Villagrana
authors.forename: Aaron
authors.initials: A
authors.lastname: Benjamin
authors.forename: Subhash
authors.initials: S
authors.lastname: Kukreja
authors.forename: Elena
authors.initials: E
authors.lastname: Barengolts
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000328:Adult; D001213:Asian; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D002112:Calcifediol / Q000097:blood*; D002641:Chicago / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006785:Hospitals, University; D006786:Hospitals, Urban; D006801:Humans; D007396:Internship and Residency; D010281:Parathyroid Hormone / Q000097:blood; D015995:Prevalence; D011446:Prospective Studies; D013337:Students, Medical; D011795:Surveys and Questionnaires; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D044465:White People; D055815:Young Adult
chemical_list: C470125:PTH protein, human; D010281:Parathyroid Hormone; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol