Osteoporosis Diagnosis: Bone Density Test?>

As a patient ages, some decrease in bone density is expected due to the slowdown of the bone remodeling cycle. Primarily two types of cells are involved in the remodeling cycle.

During remodeling, osteoclasts break down areas of decreased density and osteoblasts rebuild and remodel the areas left vacant by the osteoclasts.

The function of these two types of cells is supported by a sufficient supply of the minerals and vitamins needed for this exchange. Remodeling occurs rapidly in children and is responsible for the rapid growth in the skeleton seen during childhood. This process slows in the mid to late twenties once the person has reached full skeletal maturity.

Remodeling in the normal (non-osteoporotic) adult occurs at a steady rate and maximum bone density is achieved by age thirty. At this point, remodeling slows somewhat. Slight bone loss seen after this age is expected and considered normal. The hormonal changes associated with menopause can accelerate this loss and explains why most cases of osteoporosis in women are diagnosed after age fifty.

Do I Have Osteoporosis?

Only your physician can determine if you have experienced changes in bone density. Often patients don't know that they're at risk, or that they are already affected. Screening tests, similar to low radiation x-rays, are commonly used to scan the heel, the wrists, the spine, or even the whole body to find weakened points or potential hairline fractures.

Osteoporosis Risk Factors

• inadequate calcium and vitamin D intake
• family history
• never having given birth
• smoking
• alcohol intake of more than two drinks per day
• early or surgical menopause without hormone replacement therapy
• small or thin frame
• Caucasian ethnicity
• sedentary lifestyle
• history of treatment with steroids, antacids with aluminum, anticonvulsant, or thyroid replacement medications.

If any of these risk factors apply to you, talk to your doctor and consider having a bone density test done.

Osteoporosis Detection: Bone Density Testing

A bone density test, also called a bone mineral density test (BMD), bone scan or densitometry, measures the strength of and mineral concentration in the skeleton. This test can help doctors determine what treatments, if any, are needed to halt existing osteoporosis and perhaps reverse the effects of the condition.

The tests are fast and easy. Several types are available with some of the most common listed here:

• Dual-energy x-ray absorptiometry (DXA), often called a "bone scan," is a low-radiation test that takes less than fifteen minutes to perform and can detect minute changes in the skeleton. While you are lying flat on your back, the x-ray machine moves over you to scan your hips and lower vertebrae.
• Quantitative computed tomography (QCT) is also performed in less than fifteen minutes. It provides a 3-dimensional image of the parts of the skeleton scanned. The monetary cost and the radiation exposure are generally higher for this method.
• Quantitative ultrasound (QUS) is another rapid test. Ultrasound is much less expensive and doesn't use radiation, however this test is usually applied to the wrist or heel and is considered less accurate than a bone scan or QCT.

The interpretation of a bone density test is performed by comparing your values to those of a "normal" population of individuals with the same age, sex, and weight. In this way, the doctor can tell you if you are in the "safe" or "at risk" zone.

Resources

ISL Consulting Co. (2003). Bone scans explained. Yahoo! Health.

Mayo Foundation for Medical Education and Research. (2003). Bone density testing: Measure your risk of broken bones.

National Osteoporosis Foundation. (updated 2004). Osteoporosis: Bone density.