title: The association between renal tubular damage and rapid renal deterioration in the Japanese population: the Takahata study.
abstract: BACKGROUND
  Injury to renal tubules plays an important role in the development of various renal diseases; however, the prevalence and significance of renal tubular damage in the general population are unclear. To clarify this point, we conducted a community-based study, using urinary β(2)-microglobulin as a marker of tubular damage.
  
  
  METHODS
  The subjects studied were 3,444 Japanese over the age of 40 years. The urinary β(2)-microglobulin-creatinine ratio (UBCR) was assessed in morning spot urine samples.
  
  
  RESULTS
  In this population, the distribution of the UBCR among these subjects was skewed towards higher values and a high UBCR (≥300 μg/g) was identified in 438 (12.7%) subjects. However, overlap with macroalbuminuria and renal insufficiency [estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2)] was observed in only 25 (5.7%) and 58 (13.2%) of these subjects, respectively. Multivariate analysis indicated that a high UBCR was positively associated with aging, hypertension, macroalbuminuria and increased urinary sodium excretion. A 5-year longitudinal analysis in 899 subjects indicated a greater decline in eGFR in parallel with the increase in baseline UBCR. After adjustment for possible confounders, a high UBCR was an independent risk factor for rapid decline in eGFR [<-10 mL/min/1.73 m(2); odds ratio 1.79 (95% confidence interval 1.07-2.99), P = 0.026].
  
  
  CONCLUSIONS
  This study showed that renal tubular damage was common and was an independent risk factor for renal deterioration in the Japanese population. More attention should be paid to occult renal tubular damage in order to prevent end-stage renal disease.
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, 2-2-2, Iida-Nishi, Yamagata 990-9585, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kudo
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Konta
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Mashima
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takasaki
authors.forename: Ami
authors.initials: A
authors.lastname: Ikeda
authors.forename: Masato
authors.initials: M
authors.lastname: Hoshikawa
authors.forename: Kazuko
authors.initials: K
authors.lastname: Suzuki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shibata
authors.forename: Tetsu
authors.initials: T
authors.lastname: Watanabe
authors.forename: Takeo
authors.initials: T
authors.lastname: Kato
authors.forename: Sumio
authors.initials: S
authors.lastname: Kawata
authors.forename: Isao
authors.initials: I
authors.lastname: Kubota
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007674:Kidney Diseases / Q000453:epidemiology / Q000209:etiology*; D007676:Kidney Failure, Chronic / Q000517:prevention & control; D007684:Kidney Tubules / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D001613:beta 2-Microglobulin / Q000652:urine
chemical_list: D001613:beta 2-Microglobulin; D003404:Creatinine