Osteoporosis: A House With Too Few Nails

Osteoporosis is a condition of bone weakness due to suboptimal calcification of the skeleton.

When the carpenter builds a house, he uses an optimal number of nails to achieve maximum strength in the resulting structure.  It is the same with our skeleton.  If our skeleton is optimally calcified, then it also will achieve maximal strength.  There is only a small window in time when we can influence the calcium concentration in our skeleton.  This is the growing period.  Once growth ceases, we can no longer increase the calcium concentration in our bones, no matter how much calcium we take in.  The best we can do is to maintain the concentration that we have.

In the adult, there are many conditions that rob the skeleton of calcium.  We call these risk factors.  Common risk factors include poor diet, smoking, excess alcohol intake, sedentary lifestyle, menopause, chronic diseases like diabetes and rheumatoid arthritis, old age, and a family history of osteoporosis.

The body needs a constant level of calcium circulating in the blood in order to function.  When the calcium level in the blood drops, the body “borrows” from the calcium stored in the bones.  This borrowed calcium is paid back if there is adequate calcium and vitamin D in our diet.  If not, this deficit persists and can lead to osteoporosis.

Calcium deficient bone is at a higher risk for fragility fractures, i.e., breaks in the bone caused by little or no trauma.  Any bone can undergo a fragility fracture.  A fragility fracture of the hip carries the greatest risk, with a mortality rate of 15% to 30%.

What can we do?

Ensure that our children receive adequate amounts of vitamin D and calcium in their diet during the growing period, between 8 and 18 years of age.  The best sources of calcium and vitamin D are fortified orange juice, diary products, and supplements.

Reduce the risk factors that we can control by lifestyle changes:  exercise, stop smoking, reduce alcohol intake, and eat a well balanced diet that includes at least 1000 mg of calcium and 400 IU of vitamin D per day.

Obtain a DEXA scan. This is an x-ray that shows just how thin the bones are and indicates the relative risk for fracture.  Absolute indications for a DEXA scan include a woman in menopause, a male over 70, and any person who has sustained a fragility fracture.

In addition to the above modalities for treating osteoporosis, physicians often recommend anti-resorptive medications called bisphosphonates.  This important class of drugs markedly reduces the risk of sustaining a fragility fracture and will be discussed in next month’s column.