A 65-year-old woman develops compression fractures of the vertebrae in the spinal column. Radiography of the spine shows generalized osteopenia and narrowing of the disk spaces. The serum calcium and phosphorus levels are normal. Which of the following most accurately describes the underlying pathogenesis responsible for this patient's radiographic findings?
A: Vitamin D deficiency
B: Increased secretion of parathyroid hormone-related peptide
C: Imbalance between osteoclastic and osteoblastic activity
D: Secretion of osteoclast activating factor by macrophages
E: Increased secretion of parathyroid hormone
diagnosis? is this pagets?
Osteoporosis is the most common metabolic abnormality of bone in the United States. There is a reduction in normal mineralized bone, resulting in decreased bone mass and bone density. Decreased bone mass and density is reflected as osteopenia in bone radiography. Estrogen deficiency after menopause is the most common cause of primary osteoporosis in women. Most of the bone is lost in the first 3 to 6 years after menopause. A partial list of secondary causes of osteoporosis includes estrogen deficiency associated with exercise-induced amenorrhea or anorexia nervosa, primary hyperparathyroidism, Cushing syndrome, chronic metabolic acidosis, heparin therapy, osteogenesis imperfecta, and the lack of gravity in space. In primary osteoporosis in women, an imbalance occurs between the resorption of bone (osteoclastic activity) and the formation of bone (osteoblastic activity) (choice C). Normally, estrogen inhibits osteoclast development in the bone marrow as well as osteoclast activity and increases osteoblastic activity in bone. Therefore, a deficiency of estrogen increases osteoclastic resorption of both cortical and trabecular bone and decreases osteoblastic bone formation. Osteoporosis increases the risk of compression fractures of the vertebral bodies, Colles' fractures, other pathologic fractures, a decrease in overall height, and œdowager's hump of the cervical spine.
Serum phosphate and calcium levels are normal in osteoporosis. The latter finding excludes vitamin D deficiency (choice A), which produces hypocalcemia, secretion of PTH-related peptide (choice B) and PTH (choice E), which produce hypercalcemia; and, also rules out increased secretion of osteoclast-activating factor by macrophages (choice D), since that produces lytic bone lesions and hypercalcemia