IMMUNOREACTIVE INSULIN-LIKE GROWTH FACTOR-II IN URINE

Insulin-like growth factor II and insulin-like growth factor binding protein-1 were identified and quantified in the urine of 23 healthy subjects between 17 and 76 years of age. IGF-II was measured after separation by gel chromatography at low pH and compared with IGF-I levels in the same samples, whereas IGF binding protein-I was measured in dialysed urine. Urinary IGF-II was found at much higher concentrations than IGF-I (mean ± SEM: 717 ± 69 vs 110 ± 5 ng/mmol creatinine). The chromatographic profile indicates that pro-IGF-II may also be present. The concentrations of IGF-II appear to be less variable than the other reported parameters. The mean IGF binding protein-1 concentrations in these urine samples was 414 ± 83 ng/mmol creatinine. IGFs in the urine are in part bound to binding proteins.