title: Early changes in biochemical markers of bone formation during teriparatide therapy correlate with improvements in vertebral strength in men with glucocorticoid-induced osteoporosis.
abstract: Changes of the bone formation marker PINP correlated positively with improvements in vertebral strength in men with glucocorticoid-induced osteoporosis (GIO) who received 18-month treatment with teriparatide, but not with risedronate. These results support the use of PINP as a surrogate marker of bone strength in GIO patients treated with teriparatide.
  
  
  BACKGROUND
  To investigate the correlations between biochemical markers of bone turnover and vertebral strength estimated by finite element analysis (FEA) in men with GIO.
  
  
  METHODS
  A total of 92 men with GIO were included in an 18-month, randomized, open-label trial of teriparatide (20 μg/day, n = 45) and risedronate (35 mg/week, n = 47). High-resolution quantitative computed tomography images of the 12th thoracic vertebra obtained at baseline, 6 and 18 months were converted into digital nonlinear FE models and subjected to anterior bending, axial compression and torsion. Stiffness and strength were computed for each model and loading mode. Serum biochemical markers of bone formation (amino-terminal-propeptide of type I collagen [PINP]) and bone resorption (type I collagen cross-linked C-telopeptide degradation fragments [CTx]) were measured at baseline, 3 months, 6 months and 18 months. A mixed-model of repeated measures analysed changes from baseline and between-group differences. Spearman correlations assessed the relationship between changes from baseline of bone markers with FEA variables.
  
  
  RESULTS
  PINP and CTx levels increased in the teriparatide group and decreased in the risedronate group. FEA-derived parameters increased in both groups, but were significantly higher at 18 months in the teriparatide group. Significant positive correlations were found between changes from baseline of PINP at 3, 6 and 18 months with changes in FE strength in the teriparatide-treated group, but not in the risedronate group.
  
  
  CONCLUSIONS
  Positive correlations between changes in a biochemical marker of bone formation and improvement of biomechanical properties support the use of PINP as a surrogate marker of bone strength in teriparatide-treated GIO patients.
authors.affiliation: West German Osteoporosis Centre, Klinikum Leverkusen, University of Cologne, Am Gesundheitspark 11, 51375, Leverkusen, Germany, parvis@farahmand.de.
authors.forename: P
authors.initials: P
authors.lastname: Farahmand
authors.forename: F
authors.initials: F
authors.lastname: Marin
authors.forename: F
authors.initials: F
authors.lastname: Hawkins
authors.forename: R
authors.initials: R
authors.lastname: Möricke
authors.forename: J D
authors.initials: JD
authors.lastname: Ringe
authors.forename: C-C
authors.initials: CC
authors.lastname: Glüer
authors.forename: N
authors.initials: N
authors.lastname: Papaioannou
authors.forename: S
authors.initials: S
authors.lastname: Minisola
authors.forename: G
authors.initials: G
authors.lastname: Martínez
authors.forename: J M
authors.initials: JM
authors.lastname: Nolla
authors.forename: C
authors.initials: C
authors.lastname: Niedhart
authors.forename: N
authors.initials: N
authors.lastname: Guañabens
authors.forename: R
authors.initials: R
authors.lastname: Nuti
authors.forename: E
authors.initials: E
authors.lastname: Martín-Mola
authors.forename: F
authors.initials: F
authors.lastname: Thomasius
authors.forename: J
authors.initials: J
authors.lastname: Peña
authors.forename: C
authors.initials: C
authors.lastname: Graeff
authors.forename: G
authors.initials: G
authors.lastname: Kapetanos
authors.forename: H
authors.initials: H
authors.lastname: Petto
authors.forename: A
authors.initials: A
authors.lastname: Gentzel
authors.forename: A
authors.initials: A
authors.lastname: Reisinger
authors.forename: P K
authors.initials: PK
authors.lastname: Zysset
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001696:Biomechanical Phenomena / Q000187:drug effects / Q000502:physiology; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D005272:Femur Neck / Q000503:physiopathology; D020342:Finite Element Analysis; D005938:Glucocorticoids / Q000009:adverse effects*; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology; D010024:Osteoporosis / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D010446:Peptide Fragments / Q000097:blood; D011347:Procollagen / Q000097:blood; D000068296:Risedronic Acid; D019379:Teriparatide / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D050071:Bone Density Conservation Agents; D005938:Glucocorticoids; D010446:Peptide Fragments; D011347:Procollagen; C047202:procollagen Type I N-terminal peptide; D019379:Teriparatide; D000068296:Risedronic Acid; D012968:Etidronic Acid