title: Characteristics of urinary and serum soluble Klotho protein in patients with different degrees of chronic kidney disease.
abstract: BACKGROUND
  Klotho is a single-pass transmembrane protein, which appears to be implicated in aging. The purpose of the present study was to characterize the relationship between the soluble Klotho level and renal function in patients with various degrees of chronic kidney disease (CKD).
  
  
  METHODS
  The levels of soluble Klotho in the serum and urine obtained from one hundred thirty-one CKD patients were determined by a sandwich enzyme-linked immunosorbent assay system.
  
  
  RESULTS
  The amount of urinary excreted Klotho during the 24 hr period ranged from 1.6 to 5178 ng/day (median 427 ng/day; interquartile range [IR] 56.8-1293.1), and the serum Klotho concentration ranged from 163.9 to 2123.7 pg/ml (median 759.7 pg/ml; IR 579.5-1069.1). The estimated glomerular filtration rate (eGFR) was significantly correlated with the log-transformed values of the amount of 24 hr urinary excreted Klotho (r = 0.407, p < 0.01) and the serum Klotho levels (r = 0.232, p < 0.01). However, a stepwise multiple regression analysis identified eGFR to be a variable independently associated only with the log-transformed value of the amount of 24-hr urinary excreted Klotho but not with the log-transformed serum Klotho concentration. Despite the strong correlation between random urine protein-to-creatinine ratio and the 24 hr urinary protein excretion (r = 0.834, p < 0.01), a moderate linear association was observed between the log-transformed value of the amount of 24 hr urinary excreted Klotho and that of the urinary Klotho-to-creatinine ratio (Klotho/Cr) in random urine specimens (r = 0.726, p < 0.01).
  
  
  CONCLUSIONS
  The amount of urinary Klotho, rather than the serum Klotho levels, should be linked to the magnitude of the functioning nephrons in CKD patients. The use of random urine Klotho/Cr as a surrogate for the amount of 24-hr urinary excreted Klotho needs to be evaluated more carefully.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-Shi, TOCHIGI, 329-0498, Japan. tetsu-a@jichi.ac.jp
authors.forename: Tetsu
authors.initials: T
authors.lastname: Akimoto
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Yoshizawa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Akihiko
authors.initials: A
authors.lastname: Numata
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Eri
authors.initials: E
authors.lastname: Takeshima
authors.forename: Kana
authors.initials: K
authors.lastname: Iwazu
authors.forename: Takanori
authors.initials: T
authors.lastname: Komada
authors.forename: Naoko
authors.initials: N
authors.lastname: Otani
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Morishita
authors.forename: Chiharu
authors.initials: C
authors.lastname: Ito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shiizaki
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ando
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Muto
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuro-o
authors.forename: Eiji
authors.initials: E
authors.lastname: Kusano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood / Q000652:urine; D005260:Female; D005966:Glucuronidase / Q000097:blood* / Q000652:urine*; D006801:Humans; D000090265:Klotho Proteins; D008297:Male; D008875:Middle Aged; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis / Q000652:urine*; D012995:Solubility; D055815:Young Adult
chemical_list: D015415:Biomarkers; D005966:Glucuronidase; D000090265:Klotho Proteins