title: Relationship between increased endogenous parathormone levels and bone density in postmenopausal women treated with bisphosphonates.
abstract: OBJECTIVE
  Bisphosphonates increase bone mineral density (BMD) and also increase parathyroid hormone (PTH): the rule of increased PTH on BMD is not well known. The aim of our study was to assess the relationship between endogenous PTH levels and BMD after 18 months of antiresorptive therapy in a group of post-menopausal women with normal baseline PTH levels.
  
  
  METHODS
  A retrospective study was conducted on 62 women with normal baseline PTH levels (mean age 62.7 ± 8.6 years) who underwent dual-energy X-ray absorptiometry, thoracic-lumbar radiography, and blood and urine sampling at the baseline and after 18 months. All patients were treated with bisphosphonates and received calcium and vitamin D3 supplementation.
  
  
  RESULTS
  In the whole group, after 18 months, mean BMD improved both at lumbar spine (0.53 ± 0.09 vs. 0.49 ± 0.09 g/cm2; P<0.05) and at femur (0.66 ± 0.08 vs. 0.65 ± 0.09 g/cm2; P<0.05); PTH levels (56.80 ± 19.07 vs. 48.74 ± 14.99 pg/mL; P<0.001) and serum 25-hydroxyvitamin D (60.73 ± 29.87 vs. 49.81 ± 26.56 ng/mL; P<0.05) increased. Dividing the patients according PTH variation (>0 or ≤ 0), the group with ΔPTH>0 had higher percentage increase of BMD at spine (8.0 ± 9% vs. 4 ± 7.5%; P<0.001) and at total hip (3 ± 9% vs. 0.49 ± 8.9%; P<0.001) while the bone alkaline phosphatase significantly decreased (-11.80 ± 2.19 vs. -4.05 ± 3.08 ug/L; P<0.001) than the other group.
  
  
  CONCLUSIONS
  Increased endogenous PTH levels seems to be associated with a higher BMD increase in patients treated with bisphosphonates for postmenopausal osteoporosis. The increase of PTH must be clarified by further investigations.
authors.affiliation: Division of Geriatrics, Department of Medicine, DIMED, University of Padua, Padua, Italy. alessandra.coin@unipd.it
authors.forename: A
authors.initials: A
authors.lastname: Coin
authors.forename: N
authors.initials: N
authors.lastname: Veronese
authors.forename: F
authors.initials: F
authors.lastname: Bolzetta
authors.forename: M
authors.initials: M
authors.lastname: De Rui
authors.forename: E
authors.initials: E
authors.lastname: Manzato
authors.forename: G
authors.initials: G
authors.lastname: Sergi
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000627:therapeutic use; D002762:Cholecalciferol / Q000627:therapeutic use; D019587:Dietary Supplements; D004164:Diphosphonates / Q000627:therapeutic use*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D010281:Parathyroid Hormone / Q000097:blood*; D012189:Retrospective Studies; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D016896:Treatment Outcome; D015854:Up-Regulation; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; C470125:PTH protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium