title: Interrelationship between bone turnover markers, calciotropic hormones and leptin in obese Saudi children.
abstract: OBJECTIVE
  Fat-bone relationship involves the interaction among endocrine, inflammatory, immune processes and bone turnover. We tried to assess the association between Leptin and bone turnover markers (OCN, β-CTx, ALP), calciotropic hormones PTH and 25(OH)D in obese Saudi children.
  
  
  METHODS
  A cross-sectional study performed with 60 obese children and 36 lean children. For all subjects, OCN, ALP, β-CTx, PTH, 25(OH)D, leptin, Ca and Pi were investigated. Levels of leptin were measured by [ELISA] method, and OCN, β-CTx, PTH and 25-(OH)D by an electrochemiluminescence immunoassay.
  
  
  RESULTS
  Sixty obese Saudi children had means weight (38.3 vs. 13.8 kg), height (121.0 vs. 91.8 cm) leptin (23.04 vs.16.88 ng/ml), PTH (31.5 vs. 14.7 pg/ml), Pi (1.67 vs. 1.54 mmol/l) were significantly higher and 25(OH)D (21.02 vs. 29.45 ng/ml) was significantly lower than controls. There was no difference in serum OCN, β-CTx, ALP and calcium between groups (p > 0.05). In the correlation study, OCN were significantly positively correlated with height, ALP, age, PTH, and β-CTx (r = 0.347, 0.32, p < 0.05), (r = 0.35, 0.51, 0.66, p < 0.01 respectively), while serum 25(OH)D was negatively correlated with PTH, weight, height and BMI (r = -0.45, -0.55, -0.55, -0.47, p < 0.01 respectively). PTH was positively correlated with leptin and β-CTx (r = 0.41, 0.44, p < 0.01), but not to ALP and BMI percentile. β-CTx correlated significantly positive with Pi (r = 0.34 p < 0.05) and ALP with BMI percentile (r = 0.42, p < 0.05). Multiple regression analysis demonstrated that PTH was predicted by leptin and β-CTx (R2 = 0.55); β-CTx by leptin and OCN (R2 = 0.498); OCN by PTH and β-CTx (R2 = 0.47); and 25(OH)D by PTH (R2 = 0.21).
  
  
  CONCLUSIONS
  The obese children had increased levels of leptin and PTH with strong associated with bone turn over markers OCN, β-CTx and deficiency of 25(OH)D which may be playing an important role in the pathogenesis of obesity and related bone metabolic risk diseases as osteoporosis and fractures.
authors.affiliation: Department of Medical Laboratories Technology, Faculty of Applied Medical Sciences, Taibah University, Al-Madina Al Mounwara, Kingdom Saudi Arabia. lobnahasan@yahoo.com.
authors.forename: L M
authors.initials: LM
authors.lastname: Saber
authors.forename: H N F
authors.initials: HN
authors.lastname: Mahran
authors.forename: H H
authors.initials: HH
authors.lastname: Baghdadi
authors.forename: Z M H
authors.initials: ZM
authors.lastname: Al Hawsawi
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D016723:Bone Remodeling / Q000502:physiology*; D002118:Calcium / Q000097:blood*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D009765:Obesity / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D015675:Osteocalcin / Q000097:blood*; D010024:Osteoporosis / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D010281:Parathyroid Hormone / Q000097:blood; D012529:Saudi Arabia / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood
chemical_list: D015415:Biomarkers; D020738:Leptin; D010281:Parathyroid Hormone; D015675:Osteocalcin; D014807:Vitamin D; D002118:Calcium