Effect of obesity on plasma insulin-like growth factor-I in cancer patients.

Starvation and malnutrition are associated with low concentrations of plasma insulin-like growth factor I (IGF-I). To evaluate the utility of IGF-I as a screening test for malnutrition, we compared plasma IGF-I concentrations with anthropometric measurements of nutritional status in 99 cancer patients. Forty-three percent of patients were overweight and 4 percent were underweight. Log IGF-I correlated negatively with body weight (r = -0.31, P = 0.002), midarm muscle area (MAMA) (r = -0.31, P = 0.001), triceps skinfold thickness (TSF) (r = -0.24, P = 0.03) and body mass index (r = -0.31, P = 0.003). In males plasma IGF-I correlated with TSF but not MAMA; in females IGF-I correlated with MAMA but not TSF, suggestive of a sexual dimorphism between plasma IGF-I and indices of adiposity. We conclude that obesity was far more prevalent than undernutrition, and that plasma IGF-I correlated negatively with indices of adiposity in a gender specific fashion. Because IGF-I is significantly reduced in the obese as well as in the malnourished, measurements of plasma IGF-I are unlikely to be of adequate clinical specificity to serve as a useful screening test for subtle alterations in nutritional status.