Bone Markers

Osteoporosis. Osteoporosis, or porous bone, is a disease characterised by low bone mass and structural deterioration of bone tissue. This means you may be more likely to get fragility fractures of the hip, spine, and wrist. Osteoporosis develops when bone resorption occurs too rapidly and bone formation fails to keep up. It is more likely to develop if your bones do not achieve their optimal mass during your bone-building years. Men (1 in 10) as well as women (1 in 4 over the age of 60) suffer from osteoporosis, a disease that can be largely prevented and treated.

Paget’s disease. Paget's disease is a chronic disorder that typically results in enlarged and deformed bones. In this disease, the breakdown and formation of bone tissue is excessive. As a result, bone can weaken, resulting in bone pain, arthritis, deformities, and fractures. It may be inherited, since the disease has been known to appear in more than one family member and some genes have been discovered which might cause the disease.  It may also be caused by a "slow virus" infection that is in your body for many years before symptoms appear. Paget's disease is rarely diagnosed in people under 40 years of age. Men and women are affected equally and can occur in any ethnic group.

Bone metastasis. Cancer cells that leave the (primary) tumour and enter the bloodstream can take up residence in nearly every tissue of the body. Bones are one of the most common sites for these circulating cells to settle and start growing again. Metastases can occur in bones that are near or far from the primary tumour site. Metastatic bone disease is not the same as primary bone cancer. Primary bone cancer refers to a cancer that starts in bone. Bone metastasis and primary bone cancer differ in their risk factors, treatments, and outlook. Primary bone cancer is much less common than bone metastasis. Bone metastasis is one of the most frequent causes of pain in patients with cancer.

About half of all people who have cancer (except those with skin cancer) develop bone metastasis at some point in the course of their disease. Breast, prostate, kidney, lung, pancreas, bowel, stomach, thyroid, and ovarian cancers account for most metastases to bones. The spine is the area most often affected by bone metastasis, followed by the pelvis, hip, upper leg bones (femurs), and the skull.

Usually, bone problems are detected by radiology tests such as X-rays or magnetic resonance imaging (MRI).  Bone density (mass) using special types of very low dose X-rays is used for fracture risk assessment and the diagnosis of osteoporosis. Bone problems can also be detected by ultrasound scans that use high-frequency sound waves.

Bone markers, which are signs of the bone turnover process, are sometimes used as an aid to bone density testing when doctors are evaluating whether or not you have a bone disease. The process involves measuring markers of bone resorption, such as the telopeptides (CTX) and urine pyridinolines (PYR, DPD), and markers of bone formation, such as bone-specific alkaline phosphatase (ALP), procollagen (P1NP) and osteocalcin. Bone resorption markers can be measured in blood or urine. Bone formation markers are measured in blood.

Most often, bone markers are used to monitor therapy for bone disease and to help your doctor determine if your body is responding to treatment. Bone markers can enable your doctor to tell if you are responding to bone-strengthening therapy in a much shorter time period than the X-ray types of bone density testing. This way, your therapy can be altered if you are not responding properly to it.

There is also some evidence that bone markers can help doctors to predict which breast and prostate cancer patients are at high risk for bone metastases. Bone markers may also be able to predict a patient’s response to therapy for a bone-loss condition.

When are these tests requested?
In some cases, bone markers are requested with other bone mineral density tests to diagnose a bone disease. Usually, however, bone markers are requested periodically to monitor patients who already have a diagnosed bone condition and who are undergoing therapy to see how well they are responding to treatment.

1. How is osteoporosis treated?
Drug treatments for osteoporosis help to strengthen your bones and reduce your risk of having fractures. Most drug treatments for osteoporosis work by slowing down the activity of the cells that break down old bone (osteoclasts). These are known as ‘antiresorptive’ drugs. Some treatments stimulate the cells that build new bone (osteoblasts). These are known as ‘anabolic’ drugs. Others have less well understood ways of working that might combine both of these. The main aim of these drug treatments is to decrease the risk of breaking bones, and drugs are licensed on the basis that they do this. Often treatments will show an increase in bone density as well.
The most appropriate option will need to be discussed with your doctor.

2. How prevalent is osteoporosis?
The condition affects approximately 3 million people in the UK. Of these, 80% are women.