title: Urine creatinine excretion and clinical outcomes in CKD.
abstract: OBJECTIVE
  Twenty-four-hour urine creatinine excretion is a reliable approximation of muscle mass. Whether changes in urine creatinine predict clinical outcomes in persons with CKD is unknown. This work studied the relationship between urine creatinine and patient and renal survival in people with CKD not requiring renal replacement therapy.
  
  
  METHODS
  This longitudinal cohort study included incident stages 3-5 CKD patients referred to the renal clinic at the University Federico II in Naples between January of 1995 and December of 2005. Clinical data and urine creatinine were updated at each visit. Main outcomes were all-cause mortality and kidney failure requiring dialysis.
  
  
  RESULTS
  This study enrolled 525 individuals and followed them for a median of 6 years (range of 4 months to 15 years). Urine creatinine excretion declined by 16 mg/d per year (95% confidence interval, 14 to 19) in participants with CKD stages 3a, 3b, and 4, and it remained stable in participants with stage 5 CKD. Per each 20 mg/d decline in urine creatinine, mortality increased by 3% (adjusted hazard ratio, 1.03; 95% confidence interval, 1.01 to 1.05), and the risk of initiating dialysis increased by 2% (adjusted hazard ratio, 1.02; 95% confidence interval, 1.01 to 1.03). These associations were independent of body mass index and GFR.
  
  
  CONCLUSIONS
  In persons with CKD stages 3 and 4, urine creatinine declines at a rate of 16 mg/d per year. Lower urine creatinine excretion predicts greater risk of kidney failure and patient mortality.
authors.affiliation: Department of Medicine, Division of Nephrology, Hospital A. Landolfi, Solofra (AV), Italy;, †Departments of Medicine and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada;, ‡Division of Nephrology, Dialysis and Transplantation, University Hospital San Giovanni di Dio e Ruggi d'Aragona, Salerno, Italy, §Department of Nephrology, University of Naples "Federico II," Naples, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Di Micco
authors.forename: Robert Ross
authors.initials: RR
authors.lastname: Quinn
authors.forename: Paul Everett
authors.initials: PE
authors.lastname: Ronksley
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bellizzi
authors.forename: Adriane Marlene
authors.initials: AM
authors.lastname: Lewin
authors.forename: Bruno
authors.initials: B
authors.lastname: Cianciaruso
authors.forename: Pietro
authors.initials: P
authors.lastname: Ravani
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007558:Italy; D007668:Kidney / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D051437:Renal Insufficiency / Q000503:physiopathology / Q000652:urine; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy / Q000652:urine*; D012307:Risk Factors; D013997:Time Factors; D016482:Urinalysis / Q000379:methods
chemical_list: D015415:Biomarkers; D003404:Creatinine