Bone mineral density or BMD refers to the density of minerals contained per cubic meter of the bones in your body. A bone mineral density test will help you to assess the strength of your bones and can proactively help to identify a condition called Osteopenia. It is also used to confirm if the patient already has Osteoporosis.
Osteopenia occurs when the bone density is low and can lead to fracture of the bones. Osteopenia can eventually lead to Osteoporosis if it is not identified on time. Osteoporosis is a condition in which the bones become extremely thin and brittle, increasing the risk of the bone getting fractured.
There are many reasons that can contribute to the reduction in the density of the bone, thus leading to Osteoporosis. Some of the most well known reasons are:
The Bone Mineral density test or BMD test is usually performed using a technique called as bone densitometry. DEXA or “Dual energy x-ray absorptiometry” is the most commonly used densitometry technique. It is a painless technique and can provide precise details on even small amounts of bone density reduction. There are several other methods based on the CT Scan and ultrasound that are also used to measure bone density. These are called QCT and QUS.
The result of a BMD test is called a T-Score and is expressed as a Standard Deviation. The average BMD of a large group of healthy 30 year olds is used as a baseline to derive your T-score. After your BMD has been measured it is compared against this average.
Your T-score may be negative if your bone density is lesser than that of an average 30 year old and positive if it is higher. You may use the following scale to interpret the T-score values:
Normal: Standard deviation or SD is less than 1 indicates that you are normal. Osteopenia: SD between 1 and 2.5 shows signs of low bone density. Osteoporosis: An SD of 2.5 or greater indicating that the bones have become very fragile and thin.
It is also important to know that cancer, consuming certain types of medicine and Vitamin D deficiency, can impact the BMD.