title: A low fractional excretion of Phosphate/Fgf23 ratio is associated with severe abdominal Aortic calcification in stage 3 and 4 kidney disease patients.
abstract: BACKGROUND
  Vascular calcification (VC) contributes to high mortality rates in chronic kidney disease (CKD). High serum phosphate and FGF23 levels and impaired phosphaturic response to FGF23 may affect VC. Therefore, their relative contribution to abdominal aortic calcification (AAC) was examined in patients CKD stages 3-4.
  
  
  METHODS
  Potential risk factors for AAC, measured by the Kauppila Index (KI), were studied in 178 patients.
  
  
  RESULTS
  In multivariate linear analysis, AAC associated positively with age, male gender, CKD-stage, presence of carotid plaques (CP) and also with FGF23, but negatively with fractional excretion of phosphate (FEP). Intriguingly, FEP increased with similar slopes with elevations in PTH, with reductions in GFR, and also with elevations in FGF23 but the latter only in patients with none (KI = 0) or mild (KI = 1-5) AAC. Lack of a FEP-FGF23 correlation in patients with severe AAC (KI > 5) suggested a role for an impaired phosphaturic response to FGF23 but not to PTH in AAC. Logistic and zero-inflated analysis confirmed the independent association of age, CKD stage, male gender and CP with AAC, and also identified a threshold FEP/FGF23 ratio of 1/3.9, below which the chances for a patient of presenting severe AAC increased by 3-fold. Accordingly, KI remained unchanged as FEP/FGF23 ratios decreased from 1/1 to 1/3.9 but markedly increased in parallel with further reductions in FEP/FGF23 < 1/3.9.
  
  
  CONCLUSIONS
  In CKD 3-4, an impaired phosphaturic response to FGF23 with FEP/FGF23 < 1/3.9 associates with severe AAC independently of age, gender or CP.
authors.affiliation: Nephrology Service and Unit for the Detection and Treatment of Atherothrombotic diseases (UDETMA), Hospital Universitari Arnau de Vilanova, Av Rovira Roure, 25198 Lleida, Spain. valdivielso@medicina.udl.es.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Craver
authors.forename: Adriana
authors.initials: A
authors.lastname: Dusso
authors.forename: Montserrat
authors.initials: M
authors.lastname: Martinez-Alonso
authors.forename: Felipe
authors.initials: F
authors.lastname: Sarro
authors.forename: José M
authors.initials: JM
authors.lastname: Valdivielso
authors.forename: Elvira
authors.initials: E
authors.lastname: Fernández
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal; D001018:Aortic Diseases / Q000453:epidemiology / Q000652:urine*; D015415:Biomarkers; D002114:Calcinosis / Q000453:epidemiology* / Q000652:urine*; D015897:Comorbidity; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000652:urine*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000652:urine; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology / Q000652:urine*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013030:Spain / Q000453:epidemiology; D015996:Survival Rate
chemical_list: D015415:Biomarkers; C000717427:FGF23 protein, human; D010710:Phosphates; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23