Searching for answers to a devastating global health concern

Osteoporosis affects tens of millions of people worldwide and is responsible for as many as 75% of all fractures in people over the age of 45. Costly and disabling fractures of the spine, hip, wrist, and other bones can be preceded by years of undetected bone loss. What's more, as many as 20% of those who suffer osteoporosis-related hip fractures die within 6 months. Complications of osteoporosis are the 12th leading cause of death in America and are responsible for more deaths in women than cancers of the breast and cervix combined. Over $18 billion is spent by the US healthcare system each year. Women are at four times greater risk of developing osteoporosis than men, with postmenopausal women particularly vulnerable. Finding accurate, convenient methods of monitoring the bone loss that can lead to osteoporosis is critical in combating this crippling disease.

The physiology behind the technology
Bone is an active living tissue made of a protein framework to which various minerals attach. Throughout life, bone is constantly dissolved in a process called bone resorption and reformed in a dynamic process called bone remodeling.This is a function of two types of cells, osteoclasts (bone resorption) and osteoblasts (bone formation). As bone is resorbed by osteoclasts, bone collagen degradation fragments are released into the bloodstream and excreted in the urine.

In childhood and adolescence, bone remodeling is associated primarily with bone growth. After age 30 to 35, resorption by osteoclasts progressively outweighs formation of new bone, resulting in an increase in bone loss that can lead to osteoporosis. In postmenopausal women, this process is accelerated by declining estrogen levels.

How can I Find Out Before Its Too Late?
At present, the standard clinical method for detecting bone loss involves radiologic techniques to measure bone mineral density. These technologies, however, provide a static picture of bone mass and density at a particular point in time. Sequential measurements (usually 12 months apart or longer) are necessary to identify significant interim bone loss. Furthermore, imaging of this kind is expensive.

Various biochemical markers of bone turnover, such as urinary hydroxyproline, have been investigated as tools in managing osteoporosis. Many of these early markers however, are found in tissues other than bone and are also influenced by diet. Hydroxyproline, for example, is not specific to bone, can be affected by diet, and is metabolized extensively in the liver. Therefore, its urinary levels may not accurately reflect the degree of bone resorption.

Research has recently focused on the urinary excretion of the molecular cross-links of bone collagen, including pyridinoline and deoxypyridinoline. These pyridinoline crosslinks, however, are also found in cartilage and other connective tissues, such as ligaments tendons, fascia, and blood vessels. Moreover, the techniques used to quantify pyridinoline markers can involve a labor-intensive process.

More recently, a new marker has shown exceptional promise in its ability to specifically measure the rate of bone resorption. The marker, cross-linked N-telopeptides (NTx), is readily quantifiable and highly specific to the type I collagen found in bone. This specificity is due in large measure to the unique cross-linked amino acid sequences of the N-telopeptide chains. NTx is a direct degradation product of the bone resorption process conducted by osteoclasts. It is released into the urine in a form that cannot be broken down further and at levels that directly reflect the amount of bone collagen resorbed.

Advances in bone marker technology, exemplified by the impressive specificity of crosslinked N-telopeptides (NTx), will soon be providing clinicians with specific, convenient and noninvasive ways to assess the bone resorption rates of patients at risk for osteoporosis. With access to these important new tools, physicians will be able to monitor treatments, such as hormone replacement therapy, aimed at preventing or arresting this common debilitating disease.

Bone Loss Can Be Reversed
If your urine test indicates you may be rapidly losing bone, your doctor can identify various diseases that may cause this problem. A well balanced program of exercise, diet, hormone replacement as well as newer presecription medications may reverse this trend.

Who Should Be Tested

• Men and women over age 50
• All women who have had hysterectomies
• Heavily exercising women of all ages
• Women with a family history of osteoporosis
• Women recently pregnant or nursing
• Women with thin, petite or small frames
• People who use anti-ulcer medication
• All people with a sedentary lifestyle
• Those who consumes excessive caffeine, nicotine and alcohol
• Men and women with lactose intolerance
• All people using steroids
• Women on prolonged GnRH therapy