Age, sex, and smoking are predictors of circulating insulin-like growth factor I and insulin-like growth factor-binding protein 3

Purpose: Insulin-like growth factor (IGF-1) and its major binding protein (IGF-BP3) have recently been implicated in the pathogenesis of several malignancies. However, anthropometric and lifestyle predictors of these hormones have not been elucidated. Here we report the results of a cross-sectional study. Subjects and Methods: This cross-sectional study examines the relationship of a series of epidemiologic parameters (age, sex, height, body mass index, smoking, alcohol consumption, and coffee drinking) with IGF-1 and IGF-BP3 in a sample of 130 healthy adults. Results: We observed that serum levels of IGF-1 are higher, whereas levels of IGF-BP3 are lower, in men than in women. In addition, serum levels of IGF-1 are independently and negatively associated with age and positively associated with pack-year history of smoking. Finally, serum levels of IGF-BP3 are independently and negatively associated with the number of cigarettes smoked per day or pack-year history of smoking. Conclusion: Age, sex, and smoking are independent predictors of IGF-1 and/or IGF-BP3. The influence of these epidemiologic variables on the pathogenesis of disease states associated with IGF-1 and IGF-BP3 warrants further exploration.