Over recent years there has been considerable interest in the role of the
insulin-like growth factor (IGF) system in health and disease. It has long been known to be dysregulated in states of under- and
overnutrition, serum
IGF-I levels falling in malnourished patients and responding promptly to
nutritional support. More recently, other
proteins in this system have been observed to be dysregulated in both
malnutrition and
obesity. Currently no
biochemical marker is sufficiently specific for use in screening for
malnutrition, but levels may be valuable in providing information on nutritional status and in monitoring of
nutritional support. All have limitations as nutritional markers in that their serum levels are influenced by factors other than nutritional status, most importantly the
acute phase response (APR). Levels should be interpreted along with clinical findings and the results of other investigations such as
C-reactive protein (CRP). This paper reviews data supporting the use of
proteins of the IGF system as nutritional markers.