ANATOMY

Detailed explanation-1: -Paget’s disease is believed to be a primary disorder of increased osteoclast bone resorption with a secondary marked increase in osteoblast activity and new bone formation. The resulting trabecular bone is abnormal in that it has a “woven, ” disorganized appearance.

Detailed explanation-2: -The osteoclasts remove bone by dissolving the mineral and breaking down the matrix in a process that is called bone resorption. The osteoclasts come from the same precursor cells in the bone marrow that produce white blood cells.

Detailed explanation-3: -In Paget’s disease, osteoclasts are more active than osteoblasts (Figure 1). This means there is more bone absorption than normal. The osteoblasts try to keep up by making new bone, but they overreact and make excess bone that is very chaotic (Figure 2).

Detailed explanation-4: -Parathyroid hormone (PTH) is an important contributor to the bone remodeling process. High levels of PTH can activate osteoclasts and cause excessive bone breakdown. Calcium in your blood triggers the release of PTH. Low calcium levels in the blood, or hypocalcemia, can cause high levels of PTH.

Detailed explanation-5: -In osteoporosis, bone resorption greatly outpaces bone deposition, causing a reduction of bone density and deterioration of bone architecture such that bones are fragile and susceptible to fracture. Osteoporosis is mainly seen in older women due to decreased estrogen levels following menopause.