Hormones and osteoporosis

Abstract

Osteoporosis and its complications - bone fractures - represent a significant medical and social problem. Due to osteoporosis, bone fractures occur annually in 1.3 million Americans and 40 thousand Canadians. In France, one in two, and in Australia, one in five women aged about 70 years, suffer from fractures caused by osteoporosis. The occurrence of osteoporosis in old women is due to a decrease in estrogen production. However, a decrease in bone mineral density occurs not only with age, but even more so with all conditions leading to a change in the balance of hormones of the hypothalamic-pituitary system, thyroid and parathyroid glands, and adrenal glands. In connection with the stated purpose of this work was a synthesis of literature data on the effect of hormones on the occurrence and development of osteoporosis. Bone tissue is a dynamic metabolically active system. Depending on the function performed, cortical and trabecular bone are distinguished. The first makes up three quarters of the entire skeletal mass, forms the diaphysis of the tubular bones, has a low porosity, performs the function of supporting soft tissues and transmitting muscle contraction from one part of the body to another. Trabecular bone tissue makes up one fourth of the mass of the skeleton, forms the bones of the axial skeleton and the epiphysis of the tubular bones, has high porosity and ensures normal vital activity of the bone marrow. To do this, in the trabecular bones there are cavities ranging in size from 500 to 1000 microns, located between bone plates 100-150 microns thick. The basis of the vital activity of bone tissue is the functioning of two types of cells: osteoclasts resorbing the bone, and osteoblasts responsible for its formation. The ancestors of these cells are not fully understood, although hematopoietic monocyte macrophages are considered the most probable for osteoclasts, and stromal cells for osteoblasts, from which preosteoblasts arise. Throughout life, there is a constant renewal of bones, manifested in the resorption of individual, very small sections of tissue, with the almost simultaneous formation of a new bone. This process is of great evolutionary importance, since it allows you to remove microtrauma and bone microcracks that arise during the life process. Annually 25% of the mass of the trabecular bones and only 2-3% of the cortical bones are renewed.