Bioactive rather than total IGF-I is involved in acute responses to nutritional interventions in CAPD patients.
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.
Brugts
Michael P
MP
Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands.
Tjiong
Hoey Lan
HL
Rietveld
Trinet
T
Wattimena
Josias L
JL
van den Berg
Jacobus W
JW
Fieren
Marien W
MW
Janssen
J A M J L
JA
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
D000596:Amino Acids; D015314:Dialysis Solutions; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D005947:Glucose