Depo Provera and Bone Mineral Density (BMD)

Osteoporosis is the thinning of bone tissue and loss of bone density over time. It can strike men as well as women; however, women are the majority of victims of this condition. Women are four times more likely than men to develop osteoporosis. There are no symptoms in the early stages of the disease. Symptoms occurring late in the disease include:

· bone pain or tenderness

· fractures with little or no trauma

· loss of height (as much as six inches) over time

· low back pain due to fractures of the spinal bones

· neck pain due to fractures of the spinal bones

· stopped posture or kyphosis, also called a "dowager's hump"

We most frequently associate osteoporosis with women who are older and post-menopausal. But, it sometimes affects young people, including premenopausal women in their 20s, 30s, and 40s. Premenopausal refers to women who are still having their regular menstrual periods and have not yet reached menopause, which usually occurs in the late 40s and early 50s.

Osteoporosis occurs when the body fails to form enough new bone, when too much old bone is reabsorbed by the body, or both. There are several causes of osteoporosis, including underlying medical conditions and the use medications that can deteriorate bone mineral density (BMD). Sometimes there is no specific cause for the osteoporosis. This is called idiopathic (no known cause) osteoporosis.

Depo Provera and Bone Mineral Density

One such medication that affects BMD in young women, including teens, is the birth control shot, Depo Provera. Concerns regarding the potential dangers of this method of birth control have been voiced for more than 20 years. One major concern that was put to rest finally through the many research studies over the years confirms that Depo Provera does not increase women's risk of breast cancer. However, the same news is not linked to the effect Depo has on women's bone mineral density. There are still troubling questions in this regard.

Studies Show Depo Use Increased BMD Loss

Women who use Depo, also known as "the shot", experience a bone mineral density loss that puts them at higher risk for osteoporosis and bone fractures later in life. A woman who has completed menopause (post-menopausal) has an increased risk of bone fracture of 1.4 to 2.6 times that of premenopausal women if she has a BMD loss of as little as 10 to 13 percent. The concern expressed regarding the use of the Depo shot is that if a woman doesn't regain the lost bone mineral density after cessation of Depo, she may be more vulnerable to fractures and osteoporosis.

The fact that Depo does indeed have a harmful effect upon BMD in some women was revealed in data released to the FDA by Pfizer, the company that owns Depo Provera, in 2004. The BMD loss is thought to be connected to the suppression of the ovarian production of a hormone called estradiol, a sex hormone that is related to the development of BMD and attainment of peak bone mass.

Adolescent Bone Mineral Loss and Depo Use

The development of peak bone mass is 90 percent complete by the age of 18, which is why BMD loss and recovery is of particular importance to adolescents and young women using the shot. According to the US Surgeon General, adolescent girls "experience their most rapid rate of bone growth during puberty and, by the end of puberty, they have almost achieved peak mass." There is research showing that young women between the ages of 18 to 21 who are Depo users experience greater loss and reduced rebuilding of BMD than older women. This information is very concerning. This means that young women are losing bone mineral density at precisely the time their bodies should be amassing it. The result in coming years could mean a propensity for easily broken bones and osteoporosis.

It is not only adolescents who are at risk. A 2008 study found that women who used Depo before the age of 20 through the age of 35 had a five percent bone density deficit at the spine and hip after two years of use. A 2010 study found that after two years of Depo use, almost half of the women in the study (47.4 percent) had lost at least 5 percent BMD at the neck or spine.


Is There BMD Restoration After Depo?

The research on the restoration of bone mineral density after cessation of Depo shots is contradictory and not all studies have shown the complete recovery and restoration of BMD. The length of time associated with recovery is dependent upon the place of bone loss with the neck and hip areas being slower in recovery than the spine. So far, there is no research specifically aimed at the impact of BMD loss caused by Depo on osteoporosis or bone fractures. One study done in 2005 measured BMD in young women who had stopped using Depo for a year or more and BMD levels were as high as those in the control group with variations based on the area of bone tested. A longer term study published in 2010 found that BMD began to increase in adolescents soon after they stopped using the shot; however, BMD levels at the hip took nearly five years to return to baseline.

The length of time it takes for bone mineral density to be restored, coupled with the fact that in some cases it may never be fully restored after using the shot, highlights the need to make a careful and informed choice, particularly for young women (especially those whose BMD is still developing) in the use of Depo Provera.

You can learn more about Depo Provera here.

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