“Osteo” means bone and “penia” indicates a state of being low in quantity. The term osteopenia refers to a bone density which is somewhat less, but not excessively less, than a “standard” young person (someone in their mid to late 20s) of the same gender. If your bone density measurement indicates that your bone density is between 1.0 and 2.49 standard deviations (SD) below what would be expected in the average young man or woman, then you are said to have a bone density in the osteopenic range. You are said to have osteopenia.
Osteopenia, however, is not a disease or even a true diagnosis. It merely indicates a state of relatively low bone mass — that is, your bone mass is low when compared to the standard. You could have “osteopenia” because you never developed a high peak bone mass in your youth, or because you naturally have bones that are less dense than average (often the case with naturally slender people). It does not have to mean that you are currently losing bone.
On the other hand, some of us with osteopenia are currently undergoing bone loss and on our way to having a higher degree of bone loss, known as osteoporosis.
Recent surveys suggest that a large percentage of individuals in the US have a bone density that’s on the low side, and could be classified as having osteopenia. According to the National Osteoporosis Foundation, some 21.8 million American women and another 11.8 million men have osteopenia.
While low bone density is one of the risk factors for osteoporotic fracture, having osteopenia does not predict future fracture. In fact various studies document that well over half of those who suffer a low-trauma “osteoporotic” fracture do not have an osteoporotic bone density. Rather they have “osteopenia,” or even normal bone density.
Here are just a few references substantiating the fact that most fractures occur in people with osteopenia.
Stone, K.L. et al. 2003. BMD at multiple sites and risk of fracture of multiple types: Long-term results from the study of osteoporotic fractures. Journal of Bone and Mineral Research, 18(11):1947-1954.
Siris, E.S. et al. 2001. Identification and fracture outcomes of undiagnosed low bone mineral density in postmenopausal women: results from the National Osteoporosis Risk Assessment. JAMA, 286(22):2815-2822.
Seeman, E., et al. 2008. Strontium ranelate reduces the risk of vertebral fractures in patients with osteopenia. Journal of Bone and Mineral Research, 23(3):433-438.
So what does it matter that your bone density is 1.0 standard deviation (SD) below that of a young person? One way to look at this is to realize that a bone loss of more than 1 SD equals a 10–12% decrease in bone density. Another perspective is that you probably have a bone density that is lower than 84% of the young people of your gender. A final way to look at it is to say that in a young, healthy population, the statistics being used show that about 16% of all young women will have a T-score that is less than -1, and thus have osteopenia.
Remember, if you are not young, you will most likely not have the bone density of a young person. Also know that there is a great deal of controversy regarding how the “ideal” reference bone mineral density is established — different people accept different age groups (some say mid 20s, some late 20s, some early 30s) as the standard for average peak bone density. Currently, each manufacturer of each bone density measurement machine decides on its own “ideal” young person bone density reference range.
Often studies using locally developed reference ranges come up with very different results than those using the manufacturers’ reference range. For example, in the U.S. NHANES III trial, the bone mineral density of a diverse sample of young women was used as the reference range, which cut the prevalence of osteoporosis, as defined by bone mineral density, by more than half. If the DEXA machines’ manufacturers’ reference ranges had been used in this study, the prevalence of osteoporosis of the hip would have been 49%, rather than the 28% they reported. (For more information on the controversy surrounding ideal bone mineral reference ranges, see Gillian Sanson’s book, The Myth of Osteoporosis.)
In short, the “diagnosis” of osteopenia is something that is not cut and dried. If there are other indications that you’re losing bone, then it might be a signal to start paying closer attention to your bone health and consider taking steps to alter your diet and nutritional status. If, on the other hand, there are no signs of bone loss, and you have a healthy diet and lifestyle, being told you’re osteopenic is not a major concern — the fact that you’re “below average” density may be a normal situation for you, and not a sign of a health problem. To learn more on the topic of osteoporosis and bone loss, read our additional articles here:
4 Steps To Take After You Get an Osteopenia Diagnosis