Bone-Related Diseases

**113**

**Chapter 7**

**Abstract**

Osteoporosis

*Ayotunde Oladunni Ale*

postmenopausal women

**1. Introduction**

Thyroid Disorders and

Adequate amount of thyroid hormone is an essential requirement for normal development and maturity of bones in the early life as well as for the maintenance of the skeletal system (bone remodeling). Osteoporosis, one of the most common metabolic bone disorders, is strongly associated with hyperthyroidism (endogenous and exogenous), whereas association of the same disease with hypothyroidism is not quite established. Most of the data describing the association between osteoporosis and hyperthyroidism are collected among elderly population (especially postmenopausal women), and only a few studies in literature researched into osteoporosis and hyperthyroidism in <50 years of age; hence further studies are required in the younger population (including premenopausal women and younger males).

The skeletal system maintains a dynamic characteristic throughout its life by continuously undergoing bone modeling and bone remodeling processes [1–7]. Both bone modeling and remodeling processes include bone resorption mediated by osteoclasts and bone formation mediated by osteoblasts. Bone modeling is the predominant event during childhood, whereas in adults bone remodeling is the principal event [8]. In the case of bone modeling, both bone resorption and bone formation lead to major cur independently of one another at different sites of the skeletal system and lead to major change in the skeletal framework, whereas in the case of bone remodeling, both the processes of bone resorption and formation are closely related both in terms of time and site so that bone volume and density both remain more or less unchanged. The continuous process of bone remodeling repairs micro fractures, prevents formation of brittle bones, and

A number of systemic and local factors regulate the process of bone remodeling. Whenever the tightly coupled processes of bone resorption and bone formation in bone remodeling are disturbed, bone mineral diseases occur, excessive bone resorption leads to osteoporosis, and excessive bone formation leads to osteopetrosis [9]. Osteoblasts and osteoclasts are the two key players of bone remodeling; other cells involved in the process are osteocytes (derived from osteoblasts and acting as mechanosensor) and the bone lining cells [9]. The process of bone remodeling increases with aging; in both perimenopausal and menopausal women, the remod-

**Keywords:** bone remodeling, hyperthyroidism, hypothyroidism,

balances calcium and phosphate homeostasis [6–8].

eling is faster than premenopausal women [9].
