Changes in profiles of circulating insulin-like growth factor components during hormone replacement therapy according to the responsiveness to therapy in postmenopausal women

OBJECTIVES: Objectives of this study were (1) to evaluate the changes in the profiles of circulating insulinlike growth factor and of insulin-like growth factor-binding proteins during hormone replacement therapy and their relation with responsiveness to hormone replacement therapy and (2) to investigate the relationship between the changes in these insulin-like growth factor components and the annual changes in bone mineral density in postmenopausal women. STUDY DESIGN: Insulin-like growth factor and insulin-like growth factor-binding proteins were measured by immunoradiometric assay and Western ligand blotting in sera from 39 postmenopausal women treated with sequential hormone replacement therapy for 1 year. Bone mineral density at the lumbar spine and the proximal portion of the femur was determined by dual-energy x-ray absorptiometry. RESULTS: No significant change in the serum levels of insulin-like growth factor II and insulin-like growth factor-binding protein was noted during hormone replacement therapy in either the responders to therapy or the nonresponders (women with >3% bone loss per year), but serum levels of insulin-like growth factor I and proportions of insulin-like growth factor-binding proteins 1, 2, and 4 decreased during hormone replacement therapy only in the former group. Changes in insulin-like growth factor components during hormone replacement therapy did not correlate with annual bone mineral density changes. CONCLUSION: Profiles of circulating insulin-like growth factor I and insulin-like growth factor-binding proteins might be involved in responsiveness to hormone replacement therapy but changes in these components during hormone replacement therapy do not predict annual changes in bone mineral density.