The relationship among serum insulin-like growth factor-I, insulin-like growth factor-I gene polymorphism, and bone mineral density in postmenopausal women in Korea

OBJECTIVE: The objective of this study was to test the hypothesis that the cytosine-adenine polymorphism in the insulin-like growth factor-I gene is associated with serum insulin-like growth factor-I levels and bone mineral density. STUDY DESIGN: The insulin-like growth factor-I cytosine-adenine polymorphism was analyzed in 300 postmenopausal Korean women. Serum insulin-like growth factor-I, bone alkaline phosphatase, and carboxy-terminal cross-linking telopeptide of type I collagen were measured by immunoradiometric assay and enzyme-linked immunosorbent assay. Bone mineral density at the lumbar spine and proximal femur was determined by dual energy radiograph absorptiometry. RESULTS: Serum insulin-like growth factord and bone mineral density levels in women who were homozygous for a 194-base pair allele were significantly higher than those levels in the 194-base pair heterozygotes or women who did not possess the 194-base pair allele. A significantly decreased prevalence of the 194/194 genotype was observed in the combined group of women with osteopenia and osteoporosis, compared with normal women. No correlation between insulin-like growth factor-I genotypes and bone turnover markers was found. CONCLUSION: The insulin-like growth factor-I gene cytosine-adenine polymorphism relates with circulating insulin-like growth factor-I levels and bone mineral density at the lumbar spine and proximal femur.