What Is Osteoporosis?

This article starts below.

Osteoporosis is a systemic skeletal disease of compromised bone strength leading to an increased risk of fracture. Osteoporosis is considered a global health problem being a major cause of morbidity in the elderly.

The fractures associated with osteoporosis cause considerable disability and loss of quality of life and can be fatal. Up to half the bone loss experienced by women is attributable to loss of estrogen. Currently, one in every three women is suffering from this silent disease.

Osteoporosis is defined by bone mineral density measurement according to the WHO criteria:

  • Normal bone density: T-score more than or equal to -1
  • Osteopenia (low bone mass): T-score between -1 and -2.5
  • Osteoporosis: T-score less than or equal to -2.5
  • Severe osteoporosis: T-score less than or equal to -2.5 with fragility fracture

Diagnosis of Osteoporosis

The diagnosis of osteoporosis may be done by measure the bone mineral density. Peripheral bone densitometry and bone turnover markers may be useful in selected patients.

Techniques for measuring BMD

Since bone strength reflects bone density and bone quality, bone mineral density (BMD) has been the standard measurement for the diagnosis of osteoporosis. Central dual x-ray absorptiometry (DXA) is currently considered the gold standard for the diagnosis of osteoporosis.

Skeletal sites for BMD measurement and regions of interest include the spine (preferable L1 to L4), the hip (total, neck, or trochanter), or the forearm (33 percent radius or one-third radius).

Peripheral bone densitometry

Peripheral devices are useful for assessment of fracture risk. However, clinical utility of peripheral bone densitometers in the diagnosis of osteoporosis needs to be carefully studied. Based on the International Society for Clinical Densitometry Position Statement, the WHO criteria for diagnosis of osteoporosis and osteopenia should not be used with peripheral BMD measurement other than 33 percent radius.

Bone turnover markers

Measurements of bone turnover markers (BTM) can predict future fracture risk. The following biochemical markers of bone turnover can be measured in serum and urine:

  • markers of bone formation (bone specific alkaline phosphatase, procollagen type I propeptides, osteocalcin)
  • markes of bone resorption (deoxypyridinoline cross-links [in urine], C and N telopeptides of type I collagen cross-link)

Both bone mineral density and bone turnover marker measurement are related to fracture risk and correlate very well with fracture protection. There is a non-linear relationship between the magnitude of BMD change and the magnitude of fracture protection. Biochemical markers can be used to complement BMD testing for assessment of fracture risk.

Prevention of Osteoporosis

The following are considered the main components for the primary prevention of osteoporosis:

  1. Maintain an adequate calcium and vitamin D intake. Calcium is the nutrient most important for attaining peak bone mass and for preventing and treating post-menopausal osteoporosis. The Food and Nutrition Research Institute of the Philippines recommends 800 mg/day of calcium and 10-15 micrograms/day of vitamin D for men and women over the age of 50.
  2. Perform regular load-bearing activity. Exercise and activity program are only one component of a comprehensive program for the prevention of osteoporosis. Exercise benefits include decreased risk of falling, improved bone mass and strength, enhanced muscle strength, improved balance, better posture, increased flexibility of soft tissues, better range of motion, improved cardiovascular fitness, improved depression, and a better quality of life.
  3. Smoking cessation. Excessive bone loss occurs in smokers. Smoking has been reported to impair osteoblast or bone forming cell function, resulting to early menopause, lower body weight, and lower estrogen levels. Poor calcium absorption found in postmenopausal women who smoke is caused by a decrease in serum parathyroid hormone, leading to decreased activation of vitamin D.
  4. Avoid alcoholism. Alcohol consumption has also been associated with osteoporosis. There has been reports on the relationship between average number of drinks per day and bone density in premenopausal women.
  5. Fall prevention. Walking aids such as canes and walkers allow continued independent mobility in many elderly patients, but care must be used to avoid falls during their use. Hip strengthening exercises and the slow movement martial arts exercise, Tai Chi, have been shown to improve several physical performance measures and psychosocial indicators as well as lowering the risk of falls by 40 percent.
  6. Hip protectors. Hip protective pads, worn in side pockets of stretchy undergarments, protect against hip fractures in an elderly nursing home population (average age 81 years). While regular use and compliance is another issue, these devices are considered for elderly individuals at risk for hip fracture.

Osteoporosis Risk Factors

The established risk factors for osteoporosis are grouped into major categories:

  • age or age-related (body mass index less than 19 for Asians)
  • genetic (parental history of hip fracture)
  • environmental (use of corticosteroids longer than 3 months)
  • estrogen or androgen deficiency and chronic diseases (malabsorption, hyperthyroidism)
  • physical characteristics of bone

These risk factors cannot, however, replace bone mineral density (BMD) measurements in predicting fractures, but rather identify high risk group of individuals who should undergo dual x-ray absorptiometry (DXA) examination and screening.

Of the different determinants of bone strength, only BMD and bone turnover can be measured in patients with osteoporosis. There is good correlation between BMD and fracture risk. A reduction in the femoral neck bone mineral density increases the risk of hip fracture by a factor of two.

Excerpt from the National Guidelines for Osteoporosis Diagnosis, Prevention and Treatment