title: Urinary creatinine excretion reflecting muscle mass is a predictor of mortality and graft loss in renal transplant recipients.
abstract: BACKGROUND
  Insulin resistance has been implicated to underlie both excess cardiovascular disease and chronic transplant dysfunction after renal transplantation. Skeletal muscle mainly determines peripheral insulin resistance, and could therefore affect outcome.
  
  
  METHODS
  All transplant recipients at our outpatient clinic with a functioning graft more than 1 year were invited to participate between 2001 and 2003. Mortality and death censored graft loss were recorded until August 2007. We used 24 hr urine creatinine excretion as measure of muscle mass. Cox regression was used to analyze the prospective data.
  
  
  RESULTS
  Six hundred four renal transplant recipients (age 51+/-12 years, 55% men) were studied. Creatinine excretion was 10.1+/-2.6 mmol/24 hr in women and 13.6+/-3.4 mmol/24 hr in men. During follow-up of 5.3 (4.7-5.7) years, 95 recipients died and 42 suffered graft loss. Determinants of creatinine excretion were weight, sex, age, height, cumulative prednisolone doses, and diabetes (r2=0.45). Creatinine excretion was associated with both mortality (3rd vs. 1st tertile Hazard ratio: 0.4 [95% confidence interval 0.2-0.7], P=0.003) and graft loss (3rd vs. 1st tertile Hazard ratio: 0.4 [95% confidence interval 0.1-0.9], P=0.03) independent of age, sex, serum creatinine, proteinuria, insulin resistance related factors, time after transplantation, and duration of dialysis.
  
  
  CONCLUSIONS
  Creatinine excretion as measure of muscle mass is associated with mortality and graft loss after renal transplantation, independent of insulin resistance and its related factors. We speculate that preservation of muscle mass by stimulating exercise, sufficient diet, and less use of corticosteroids may be relevant for improving prognosis in renal transplant recipients.
authors.affiliation: Department of Medicine, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Leendert H
authors.initials: LH
authors.lastname: Oterdoom
authors.forename: Rutger M
authors.initials: RM
authors.lastname: van Ree
authors.forename: Aiko P J
authors.initials: AP
authors.lastname: de Vries
authors.forename: Ron T
authors.initials: RT
authors.lastname: Gansevoort
authors.forename: Jan P
authors.initials: JP
authors.lastname: Schouten
authors.forename: Willem J
authors.initials: WJ
authors.lastname: van Son
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: Homan van der Heide
authors.forename: Gerjan
authors.initials: G
authors.lastname: Navis
authors.forename: Paul E
authors.initials: PE
authors.lastname: de Jong
authors.forename: Reinold O B
authors.initials: RO
authors.lastname: Gans
authors.forename: Stephan J L
authors.initials: SJ
authors.lastname: Bakker
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine*; D015536:Down-Regulation; D005260:Female; D006084:Graft Rejection / Q000209:etiology* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D006085:Graft Survival; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects / Q000401:mortality; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D016017:Odds Ratio; D009929:Organ Size; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D003404:Creatinine