Vitamin D is synthesized in the skin when it's exposed to direct sunlight; its initially inactive but then is activated by the liver and kidney. Vitamin D facilitates the absorption of calcium. Calcium is the major component of bone that confers strength. Low calcium can lead to osteoporosis. In osteoporosis, there is disruption of the architectural framework of bone which weakens it; this increases likelihood for fractures.
Calcium Regulation and Sunlight
The absorption of calcium from the intestines is facilitated by vitamin D; without effective absorption of calcium, the bones becomes the chief source of calcium. Lack of sunlight exposure can lead to low vitamin D, resulting in poor absorption of calcium. Low blood calcium, stimulates the parathyroid gland to produce parathyroid hormone, which acts on bone, causing it to break down and thereby releasing calcium into the bloodstream. Excess parathyroid hormone further complicates an already weak bone. The thyroid gland produces calcitonin in response to elevated calcium in blood; calcitonin causes the removal of calcium from the blood.
Osteoporosis can occur due to low blood calcium or due to increased breakdown of bone. Diseases that lead to osteoporosis prevent the use of calcium in maintaining bone. Its not just important to maintain adequate intake of calcium but also the intake of vitamin D, since it's needed for calcium absorption.
Risk Factors
The risk for osteoporosis increases with advanced age in both men and women. Women are at a higher risk for osteoporosis because the sex hormone estrogen becomes deficient in menopause, leading to a rapid loss in bone strength. In men, a drop in the male sex hormone, testosterone, has less effect on bone density.
Excess alcohol and smoking are major risk factors for osteoporosis. Other risk factors include lack of sunlight exposure, vitamin D deficiency and malnutrition. Being physically inactive can also cause a major loss in bone strength.
Associated Signs and Symptoms
Osteoporosis has no specific symptoms but is associated with bone fractures that occur without significant stress on bones. Fractures can occur anywhere throughout the body. When it occurs in the back, it can affect posture and reduce mobility. Fracture of a long bone, such as the thigh, is a serious complication that will require surgery.
The elderly have increased risk for falls; osteoporosis increases the likelihood of fractures associated with falls.
Prevention/Solution
Osteoporosis can be prevented by making changes to lifestyle. Adequate sunlight exposure helps to prevent osteoporosis. Vitamin D is synthesized in the skin under direct sunlight. Quitting smoking and drinking are big steps in preventing osteoporosis. Bones weaken as you age, but regular weight-bearing exercise, such as walking and jogging, slows down the loss in bone strength. Exercise should be at least 30 minutes a day at least four days per week. Proper dietary intake of vitamin D and calcium can prevent osteoporosis. Diet should include intake of fish, eggs, vitamin D-fortified milk and cod liver oil; these are abundant sources of vitamin D.
Treatment
Bisphosphonates such as sodium alendronate, brand name Fosamax, risedronate, brand name Actonel or ibandronate, brand name Boniva, are preferred treatment for confirmed osteoporosis. These drugs are effective in reducing the risk of fracture. Oral bisphosphonates, must be taken on an empty stomach. Bisphosphonates are only available through a prescription.
Estrogen, is important in maintaining normal bone density in women. Post-menopausal women, are unable to make estrogen, which increases the risk for osteoporosis; in these women estrogen replacement is effective in preventing osteoporosis.
Vitamin D and calcium must be used in conjunction with other treatment s, since studies have not consistently demonstrated their effectiveness in preventing osteoporotic fractures. The supplementation of vitamin D should be at doses of 400 to 600 international units, or IUs, per day; it should be supplemented with calcium at doses of 500 to 1,200mg, per day.
