title: In chronic kidney disease, serum α-Klotho is related to serum bicarbonate and proteinuria.
abstract: OBJECTIVE
  Klotho is an "aging-suppressor" gene and encodes a single-pass transmembrane protein predominantly expressed in renal tubules. Whether chronic kidney disease (CKD) affects serum Klotho is poorly documented. We aimed to measure the relationship of serum α-Klotho with renal function, acid-base status, bone biomarkers, and proteinuria in CKD patients.
  We measured serum α-Klotho, serum FGF23, and glomerular filtration rate by inulin clearance in 60 CKD patients between January and July 2011. We also measured serum creatinine, bicarbonate, calcium, phosphorus, parathyroid hormone, C-reactive protein, and 25-OH vitamin D. Proteinuria was obtained from a 24-h urine collection.
  
  
  RESULTS
  The median serum α-Klotho was 478 (348-658) pg/mL. We found an inverse relationship between serum α-Klotho and serum creatinine (r = -0.36, P = .007), proteinuria (r = -0.36, P = .013), and a positive relationship with serum bicarbonate (r = 0.33, P = .011). There was no further significant relation between serum α-Klotho and inulin clearance or serum FGF23. Multiple regression analysis including serum bicarbonate, serum creatinine, and proteinuria indicated that only serum bicarbonate was associated with serum α-Klotho (P = .003).
  
  
  CONCLUSIONS
  This study shows that in CKD, serum α-Klotho is related to serum bicarbonate and proteinuria and not to renal function. Further research is required to determine whether correcting these 2 amenable conditions would improve serum α-Klotho.
authors.affiliation: Département de Néphrologie-Dialyse-Nutrition, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Pierre Bénite, France.
authors.forename: Valerie
authors.initials: V
authors.lastname: Hage
authors.affiliation: Département de Néphrologie-Dialyse-Nutrition, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Pierre Bénite, France; Service d'Explorations Fonctionnelles Rénales et Métaboliques, Hôpital Edouard Herriot, Lyon, France; INSERM U1033, Hôpital Edouard HERRIOT, Lyon, France.
authors.forename: Solenne
authors.initials: S
authors.lastname: Pelletier
authors.affiliation: Service d'Explorations Fonctionnelles Rénales et Métaboliques, Hôpital Edouard Herriot, Lyon, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Dubourg
authors.affiliation: Laboratoire de Biochimie, Centre Hospitalier Lyon-Sud, Pierre Bénite, France; INSERM 1060 CARMEN CENS Université de Lyon, F-69622 Lyon, France.
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Drai
authors.affiliation: Laboratoire de Biochimie, Centre Hospitalier Lyon-Sud, Pierre Bénite, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Cuerq
authors.affiliation: Service d'Explorations Fonctionnelles Rénales et Métaboliques, Hôpital Edouard Herriot, Lyon, France; INSERM 1060 CARMEN CENS Université de Lyon, F-69622 Lyon, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Lemoine
authors.affiliation: Service d'Explorations Fonctionnelles Rénales et Métaboliques, Hôpital Edouard Herriot, Lyon, France.
authors.forename: Aoumeur
authors.initials: A
authors.lastname: Hadj-Aissa
authors.affiliation: Département de Néphrologie-Dialyse-Nutrition, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Pierre Bénite, France; INSERM 1060 CARMEN CENS Université de Lyon, F-69622 Lyon, France.
authors.forename: Maurice
authors.initials: M
authors.lastname: Laville
authors.affiliation: Département de Néphrologie-Dialyse-Nutrition, Centre Hospitalier Lyon-Sud, Hospices Civils de Lyon, Pierre Bénite, France; INSERM 1060 CARMEN CENS Université de Lyon, F-69622 Lyon, France. Electronic address: denis.fouque@chu-lyon.fr.
authors.forename: Denis
authors.initials: D
authors.lastname: Fouque
mesh_terms: D000328:Adult; D000375:Aging / Q000187:drug effects*; D001639:Bicarbonates / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D005919:Glomerular Filtration Rate; D005966:Glucuronidase / Q000097:blood*; D006801:Humans; D000090265:Klotho Proteins; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011507:Proteinuria / Q000097:blood*; D051436:Renal Insufficiency, Chronic / Q000097:blood*; D014807:Vitamin D / Q000097:blood
chemical_list: D001639:Bicarbonates; D015415:Biomarkers; C000717427:FGF23 protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002097:C-Reactive Protein; D003404:Creatinine; D005966:Glucuronidase; D000090265:Klotho Proteins