title: Bioactive rather than total IGF-I is involved in acute responses to nutritional interventions in CAPD patients.
abstract: BACKGROUND
  Inadequate food intake plays an important role in the development of malnutrition in continuous ambulatory peritoneal dialysis (CAPD) patients. Aim of the study. The aim of the study was to investigate in CAPD patients whether circulating insulin-like growth factor-I (IGF-I) bioactivity may offer a more sensitive index to acute nutritional interventions than total IGF-I.
  
  
  METHODS
  An open-label, randomized, crossover study of 2 days-with a 1-week interval-was performed in 12 CAPD patients in the fed state to compare a mixture of amino acids (Nutrineal 1.1%) plus glucose (AA plus G) (Physioneal 1.36% to 3.86%) dialysate versus G only as control dialysate. Fed-state conditions were created by identical liquid hourly meals. IGF-I bioactivity was measured by the kinase receptor activation assay (IGF-I KIRA); total IGF-I was measured by immunoassay.
  
  
  RESULTS
  In the fed state, both after AA plus G as well as after G dialysis IGF-I bioactivity increased compared to baseline, while no changes in circulating total IGF-I levels were observed in both treatment arms. However, the increase in IGF-I bioactivity was only significant after AA plus G dialysis (P = 0.02).
  
  
  CONCLUSIONS
  Our results provide evidence that in CAPD patients changes in circulating IGF-I bioactivity are associated with nutrient intake and that IGF-I bioactivity rather than total IGF-I is involved in acute responses to nutritional interventions in CAPD patients.
authors.affiliation: Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Brugts
authors.forename: Hoey Lan
authors.initials: HL
authors.lastname: Tjiong
authors.forename: Trinet
authors.initials: T
authors.lastname: Rietveld
authors.forename: Josias L
authors.initials: JL
authors.lastname: Wattimena
authors.forename: Jacobus W
authors.initials: JW
authors.lastname: van den Berg
authors.forename: Marien W
authors.initials: MW
authors.lastname: Fieren
authors.forename: J A M J L
authors.initials: JA
authors.lastname: Janssen
mesh_terms: D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000627:therapeutic use; D018592:Cross-Over Studies; D015314:Dialysis Solutions; D005260:Female; D005947:Glucose / Q000627:therapeutic use; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy*; D008297:Male; D044342:Malnutrition / Q000517:prevention & control*; D008875:Middle Aged; D044623:Nutrition Therapy; D009752:Nutritional Status; D010531:Peritoneal Dialysis, Continuous Ambulatory
chemical_list: D000596:Amino Acids; D015314:Dialysis Solutions; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D005947:Glucose