Hormones, Calcium and Bone Disorders
Hormones protect bone tissue. When these hormones are too low, bones can lose calcium and begin to weaken. Calcium and bone disorders involve abnormalities of bone metabolism, which is associated with several hormones, including parathyroid hormone (PTH), estrogen, testosterone as well as other factors like Vitamin D, phosphate, and magnesium. The most common of these disorders is osteoporosis. Other calcium-related conditions include hyperparathyroidism and Paget’s disease of bone, as well as many others not discussed below.
Major bone disorders include Osteomalacia (Rickets), which is a softening of bones caused by Vitamin D deficiency.
Osteoporosis is the loss of bone calcium, making bones weaken and more prone to fracture (breakage). The vertebral bodies of the spine, the upper femur (hip), and the forearm are at greatest risk. Risk factors for osteoporosis include age, loss of estrogen (menopause) in women or loss of testosterone in men, use of steroid medication (e.g. prednisone), as well as other medical conditions, such as hyperparathyroidism, vitamin D deficiency and chronic kidney disease. Bone density is best measured using Dual X-ray absorptiometry (DEXA). Bone density is reported as a T-score, which helps estimate the risk of fracture. A moderately low bone density is called osteopenia, and is usually treated with Calcium and vitamin D, along with weight-bearing (resistance) exercise.
If the bone density is greatly reduced, as in osteoporosis, treatment may also include bone-building medications, such as bisphosphonates, or other medicines to help increase bone density and reduce the risk of fracture. The potential benefits as well as the risks of bisphosphonates and other medications should be discussed with a physician familiar with the treatment of osteoporosis to determine the appropriate treatment.
Hyperparathyroidism refers to having too much parathyroid hormone (PTH) in the blood. Parathyroid hormone comes from four small parathyroid glands in the neck and helps control the level of calcium in the blood. High levels of PTH can result in increased blood calcium levels. In most cases, the calcium is only slightly increased and does not cause symptoms. However, in some cases, high calcium levels can cause symptoms of tiredness, poor concentration, low mood, bone pain, and stomach or abdominal symptoms. Hyperparathyroidism is usually caused by a benign (non-cancerous) overgrowth of one of the parathyroid glands (adenoma), but sometimes is due to an overgrowth of all four gland (hyperplasia).
Hyperparathyroidism is diagnosed by a blood test. Treatment depends on a number of factors. People who are younger or who have very high calcium levels or problems associated with high calcium (reduced kidney function, kidney stones, or osteoporosis) are usually treated with surgical removal of the problem gland. However, people who are older (over age 50 years) with only mildly elevated calcium levels and who do not have any problems associated with it, may simply have their calcium monitored periodically. As long and the calcium level is stable and does not continue to rise, surgery may not be needed. The decision about whether surgery is appropriate should be made in conjunction with a specialist (usually an endocrinologist or internist) who is familiar with the long-term management of hyperparathyroidism.
Paget's disease of bone
Paget's disease of bone refers to a disorder of the metabolism of bone (the way bones break down and are built up over time). Normally, bone undergo continuous breakdown and build-up; a process called remodeling. In Paget's disease, bone breaks down in certain areas faster than it can be built up, which results in fragile or misshapen bones. This usually involves specific areas, such as the pelvis, skull, spine and legs.
Symptoms can include bone pain, tingling or weakness, or bone deformities. It can sometimes lead to complications, including bone fractures, osteoarthritis (from stress on the joints), nerve damage (from compression), heart failure (from the work that the heart must do because of the increase in bone metabolism) and rarely bone cancer. The cause of Paget's disease is not yet know, but risk factors include older age, being male, European ancestry, or a family history of Paget's disease.
The diagnosis of Paget's disease of bone is made using blood tests, x-rays or bone scans. Treatment can involve certain medications, such as bisphosphonates, or calcitonin. In rare cases, surgery is needed to help heal fractures, re-align bones, replace damaged joints, or relieve pressure on nerves. The treatment of Paget's disease should be guided by a specialist who is familiar with the management of this condition (usually an endocrinologist, rheumatologist, or general internist).