Insulin-like growth factor I correlates with protein intake estimated from the normalized protein catabolic rate in hemodialysis patients.
OBJECTIVE
Malnutrition and catabolism are predominant problems in patients undergoing hemodialysis. The aim of this study was to clarify the relationship between insulin-like growth factor I (IGF-I), the serum levels of which are influenced by nutrition and which by itself promotes amino acid uptake, and insulin-like growth factor binding protein 1 (IGFBP-1), known to regulate serum (s) IGF-I and protein intake, in end-stage renal disease patients.


METHODS
Thirty hemodialysis patients were studied, and s-IGF-I and s-IGFBP-1 levels were measured by radioimmunoassay. The s-IGF-I method used was validated according to a reference method. The s-IGF-I standard deviation (SD) score was calculated, giving the individual deviation from the mean of a reference population. The protein intake was estimated both directly by 3-day food recall by a dietician and indirectly by normalized protein catabolic rate (PCRn).


RESULTS
The mean serum IGF-I level was 166 +/- 10 microgr;g/l, corresponding to a normal s-IGF-I SD score (0.5 +/- 0.3). S-IGFBP-1 was elevated threefold to 101 +/- 11 microg/l as compared with normal subjects. The s-albumin was 39.9 +/- 0.5 g/l and the s-bicarbonate 24 +/- 0.4 mmol/l. There were significant correlations between s-IGF-I SD score or s-IGF-I (log-transformed) and PCRn (r = 0.37, p < 0.004, and r = 0.41, p < 0.001, respectively). The s-IGF-I/s-IGFBP-1 ratio was also positively correlated with PCRn (r(s) = 0.36, p < 0.007, by Spearman's rank correlation). The s-albumin was inversely correlated with log s-IGFBP-1 (r = -0.38, p < 0.01) and positively with the s-IGF-I/s-IGFBP-1 ratio (r = 0.36, p < 0.007) but not with s-IGF-I (p < 0.13). Serum total cholesterol, triglycerides, and total body fat as percentage of body weight correlated with s-IGF-I (r = 0.47, p < 0.004, r = 0.45, p < 0.01, and r = 0.42, p < 0.004, respectively) as well as with the s-IGF-I SD score. No correlations were seen between s-IGF-I and protein or caloric intake by direct estimates from dietary food recalls.


CONCLUSIONS
The s-IGF-I and the s-IGF-I/s-IGFBP-1 ratio were correlated with estimates of protein intake of the patients calculated from urea kinetics (PCRn) but not with direct estimates by the dietitian. The s-IGF-I SD score and the ratio s-IGF-I/s-IGFBP-1 might be a tool to monitor anabolic status and to select hemodialysis patients for therapeutic intervention with recombinant human IGF-I and/or recombinant human growth hormone to counteract catabolism.
Lindgren
B F
BF
Department of Endocrinology and Diabetology, Karolinska Hospital, Stockholm, Sweden. bjorn.lindgren@fresenius-kabi.com
Friis
K
K
Ericsson
F
F
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism*; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods; D012016:Reference Values; D006435:Renal Dialysis
D004044:Dietary Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I