title: Associations between serum leptin level and bone turnover in kidney transplant recipients.
abstract: OBJECTIVE
  Obesity is associated with increased parathyroid hormone (PTH) in the general population and in patients with chronic kidney disease (CKD). A direct effect of adipose tissue on bone turnover through leptin production has been suggested, but such an association has not been explored in kidney transplant recipients.
  
  
  METHODS
  This study examined associations of serum leptin with PTH and with biomarkers of bone turnover (serum beta crosslaps [CTX, a marker of bone resorption] and osteocalcin [OC, a marker of bone formation]) in 978 kidney transplant recipients. Associations were examined in multivariable regression models. Path analyses were used to determine if the association of leptin with bone turnover is independent of PTH.
  
  
  RESULTS
  Higher leptin levels were associated with higher PTH and lower vitamin D levels, and adjustment for vitamin D attenuated the association between leptin and PTH. However, higher leptin was also significantly associated with lower levels of the bone turnover markers: 1 SD higher leptin was associated with 0.13 lower log-OC (-0.17, -0.08, P < 0.001) and 0.030 lower log-CTX (-0.045, -0.016, P < 0.001) after multivariable adjustments. Path analysis indicated that the association of leptin with PTH was mostly mediated through vitamin D, and that the association between leptin and bone turnover was independent of PTH and vitamin D.
  
  
  CONCLUSIONS
  Elevated leptin level is associated with lower bone turnover independent of its effects on serum PTH in kidney transplant recipients.
authors.affiliation: Division of Nephrology, Salem Veterans Affairs Medical Center, Salem, Virginia, USA. csaba.kovesdy@va.gov
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.forename: Miklos Z
authors.initials: MZ
authors.lastname: Molnar
authors.forename: Maria E
authors.initials: ME
authors.lastname: Czira
authors.forename: Anna
authors.initials: A
authors.lastname: Rudas
authors.forename: Akos
authors.initials: A
authors.lastname: Ujszaszi
authors.forename: Laszlo
authors.initials: L
authors.lastname: Rosivall
authors.forename: Miklos
authors.initials: M
authors.lastname: Szathmari
authors.forename: Adrian
authors.initials: A
authors.lastname: Covic
authors.forename: Andras
authors.initials: A
authors.lastname: Keszei
authors.forename: Gabriella
authors.initials: G
authors.lastname: Beko
authors.forename: Peter
authors.initials: P
authors.lastname: Lakatos
authors.forename: Janos
authors.initials: J
authors.lastname: Kosa
authors.forename: Istvan
authors.initials: I
authors.lastname: Mucsi
mesh_terms: D000328:Adult; D000368:Aged; D016723:Bone Remodeling; D024042:Collagen Type I / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D024042:Collagen Type I; D020738:Leptin; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D014807:Vitamin D; C104450:25-hydroxyvitamin D