title: Parathyroid hormone response to severe vitamin D deficiency is associated with femoral neck bone mineral density: an observational study of 405 women with hip-fracture.
abstract: OBJECTIVE
  Hip-fracture patients with vitamin D deficiency can have either secondary hyperparathyroidism or normal levels of parathyroid hormone (PTH). We hypothesized that bone mineral density (BMD) could be lower in patients with high PTH levels than in those with normal levels of PTH, irrespectively of the severity of vitamin D depletion.
  
  
  METHODS
  In this cross-sectional study, we examined 405 women who had serum 25-hydroxyvitamin D below 12ng/ml 20.0 ± 5.9 (mean ± SD) days after a hip-fracture. PTH was assessed by a chemiluminescent immunometric assay and BMD by dual-energy x-ray absorptiometry at the unfractured femoral neck.
  
  
  RESULTS
  BMD was significantly lower in the 148 women with secondary hyperparathyroidism than in the 257 with normal PTH levels: the mean T-score (SD) was -2.88 (0.93) and -2.65 (0.83), respectively, in the two groups (mean difference 0.23; 95% CI 0.05 - 0.41; P = 0.010). The association between PTH status and BMD persisted after adjustment for age, body mass index, phosphate, albumin-adjusted total calcium, 25-hydroxyvitamin D, estimated glomerular filtration rate, and magnesium (P=0.01). The presence of secondary hyperparathyroidism was significantly associated with a femoral neck T-score lower than -2.5. The adjusted odds ratio was 1.81 (95% CI 1.11 - 2.95; P=0.017).
  
  
  CONCLUSIONS
  Our results show that PTH levels in the presence of severe vitamin D deficiency were significantly associated with femoral BMD in women with hip-fracture. Prevention and treatment of vitamin D deficiency may be particularly relevant in women who develop secondary hyperparathyroidism.
authors.affiliation: Osteoporosis Research Center and Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Fondazione Opera San Camillo, Strada Santa Margherita 136, 10131, Torino, Italy. marco.di.monaco@alice.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Di Monaco
authors.affiliation: Osteoporosis Research Center and Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Fondazione Opera San Camillo, Strada Santa Margherita 136, 10131, Torino, Italy.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Castiglioni
authors.affiliation: Osteoporosis Research Center and Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Fondazione Opera San Camillo, Strada Santa Margherita 136, 10131, Torino, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Tappero
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging*; D006620:Hip Fractures / Q000097:blood / Q000000981:diagnostic imaging; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000000981:diagnostic imaging; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D