Nutrient regulation of insulin-like growth factor-I.
Insulin-like growth factor-I (IGF-I) is a nutrient-regulated growth factor. In malnutrition, serum IGF-I levels fall despite normal or elevated growth hormone (GH) levels and this is caused by resistance to GH, defects in IGF-I gene transcription and translation and mRNA instability. Because IGF-I production is sensitive to protein and energy deficiencies serum IGF-I levels may be valuable in the assessment of the nutritional status of patients with wasting diseases, including advanced renal failure. It should be recognized, however, that serum or tissue IGF-I peptide levels do not always reflect IGF-I gene expression. For example, in the K-deficient rat, kidney IGF-I levels are increased even though IGF-I mRNA levels are low. This appears to be due in part to increased sequestration by IGF-binding proteins and by decreased kidney IGF-I degradation. The increase in kidney IGF-I may contribute to the exaggerated renal growth that occurs in hypokalemia.
Rabkin
R
R
Department of Medicine, Veterans Affairs Palo Alto Health Care System, Calif. 94304, USA. rabkin@leland.stanford.edu
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D007668:Kidney / Q000503:physiopathology; D009748:Nutrition Disorders / Q000097:blood; D009747:Nutritional Physiological Phenomena / Q000502:physiology*
D007334:Insulin-Like Growth Factor I