Intradialytic parenteral nutrition abolishes the increase of insulin-like growth factor binding protein-1 (IGFBP-1) during hemodialysis and elevates the IGF-I/IGFBP-1 ratio, an anticatabolic effect?

Abstract

Summary Background Malnutrition is a severe clinical problem in hemodialysis (HD) patients. We have earlier shown that insulin-like growth factor binding protein-1 (IGFBP-1) increases during HD and may thus limit the bioavailability of free insulin-like growth factor-I (IGF-I). The present study was performed with the aim to test if intradialytic parenteral nutrition (IDPN) would influence the IGF system in HD patients with the hypothesis that IDPN would attenuate the increase of IGFBP-1 and thus alter the IGF system to give a more anticatabolic effect. Methods Nine HD patients aged 69±3 years were studied during one HD session with IDPN and one without IDPN. The nutritional product used contained 1000 kcal (1000 ml, 53 g amino acids, 75 g glucose and 50 g long chain triglycerides—soybean oil). Blood samples were collected pre- and post-dialysis. Serum concentrations of IGF-I, insulin and IGFBP-1 were determined by RIA. Results During HD without IDPN serum levels of IGFBP-1 increased from 84±21 to 139±26 μg/l ( p =0.01). In contrast IGFBP-1 tended to decrease from 126±37 to 85±18 μg/l ( p =0.087) during HD with IDPN. The difference between post- and pre-HD IGFBP-1 was significantly larger without IDPN than with IDPN (+55±17 vs. −41±21 μg/l, p =0.0056). The ratio IGF-I/IGFBP-1, indicative of free IGF-I, decreased significantly during HD without IDPN (4.5±1.6 vs. 2.8±1.1 p =0.02). In contrast, during IDPN this ratio tended to increase from 2.6±1.0 to 4.3±1.7 ( p =0.059). The difference between post- and pre-HD was −1.7±0.5 without IDPN vs. 1.6±0.7 μg/l with IDPN ( p =0.022). Without IDPN the change in IGF-I was non-significant during HD but on IDPN IGF-I serum levels increased significantly from 156±35 to 193±44 μg/l ( p =0.004). The serum levels of insulin differed significantly during HD with a decrease without IDPN and an increase with IDPN (−17±7 vs. +19±8 μg/l p =0.009). Glucose levels decreased without IDPN but remained unchanged with IDPN (5.9±0.9 to 4.1±0.4 mmol/l p =0.021 vs. 5.8±0.8 to 6.1±0.9 mmol/l NS). Conclusions IDPN blunts the increase of IGFBP-1 and the IGF-I/IGFBP-1 ratio increases. The increased IGF-I bioavailability suggests an anticatabolic effect.