Thirty-day monitoring of insulin-like growth factors and their binding proteins in intensive care unit patients

This study investigates the regulation of the insulin-like growth factors (IGFs) and their regulatory proteins in 14 critically ill patients during the 30-day period following admission to an intensive care unit (ICU). Levels of IGF-I, IGF-II, IGF binding protein-3 (IGFBP-3) and acid-labile subunit (ALS) were low on admission, and in the 8 patients whose serum IGF-I levels failed to increase over 30 days, levels of the other proteins also remained low, while IGFBP-9 proteolytic activity increased. Of these proteins, ALS correlated best with serum levels of nutritional indicators, particularly prealbumin. IGFBP-2 and IGFBP-6 levels tended to be high in critically ill patients, but showed little change over the 30-day period. In contrast, IGFBP-1 levels were high on admission, correlated with early changes in nitrogen balance, and fell rapidly during the first week. By demonstrating that the IGF-I response in ICU patients is related to changes in the IGF regulatory proteins, this study may be of value in planning therapeutic intervention using growth hormone or IGF-I.