The Phytoestrogens, Calcitonin and Thyroid Hormones: Effects on Bone Tissue

Abstract

The skeleton is a metabolically active organ that undergoes remodeling throughout life. This involves a complex process by which old bone is continuously replaced by new tissue. Bone remodeling refers to the sequential, coupled actions of osteoclasts and osteoblasts. In conditions of sex hormone deficiency during advancing age, after the menopause or andropause, the rate of remodeling increases and bone formation is reduced relative to resorption. These alterations can cause microarchitectural deterioration of bone tissues, which increases bone loss as a predisposition to the occurrence of osteoporosis (Rehman et al., 2005). However, in contrast to postmenopausal osteoporosis in women, age-related bone loss in men is less well defined.