Association of IGF-1 and IGFBP-3 with lower urinary tract symptoms in the Third National Health and Nutrition Examination Survey

BACKGROUND. Benign growth of the prostate is thought to contribute to lower urinary tract symptoms (LUTS) in older men. It is, however, unclear which factors induce prostate growth in these men. We examined the association of insulin-like growth factor (IGF)-1 and its major binding protein IGFBP-3 with LUTS in a representative US study. METHODS. We included men 60 years and older who participated in the morning session of the Third National Health and Examination Survey (NHANES III) between 1988 and 1994. Men were classified as cases (n = 91) if they reported at least three of four LUTS (nocturia, incomplete emptying, hesitancy, or weak stream) but had not had non-cancer prostate surgery in the past. Controls were men without symptoms and surgery (n = 220). All results were weighted to account for sampling probability in NHANES III. IGF-1 and IGFBP-3 were measured by ELISA and IRMA, respectively. RESULTS. After mutual adjustment, men in the highest fertile of serum IGF-1 concentration had a non-significantly higher odds of LUTS than men in the lowest fertile (odds ratio (OR) = 3.20; 95% confidence interval (CI) 0.89-11.4; p-trend = 0.09]. A high concentration of IGFBP-3 was inversely related to the odds of LUTS (OR = 0.25; 95% CI 0.08-0.81; p-trend = 0.02). CONCLUSION. A high IGFBP-3 level might affect LUTS by decreasing the bioavailability of IGF-1 or independent of IGF-1 by up-regulating apoptosis, and, thus, limiting its growth promoting effects on the prostate.