LISA CLARK: Welcome to our webcast. I'm Lisa Clark. When it comes to osteoporosis, most women think they know the basics, but with 10 million cases of osteoporosis in the U.S. alone, there's no doubt people need to know more about this serious condition, which in many cases can be prevented. What exactly is osteoporosis, and why does it occur?
Joining me today to answer these questions is Dr. Carolyn Becker, the Associate Director of the Tony Stabile Osteoporosis Center at Columbia University. Dr. Becker, thanks for being here. We appreciate it.
CAROLYN BECKER, MD: Thank you.
LISA CLARK: I guess we'd better start with the very basics. What is bone?
CAROLYN BECKER, MD: Many people think of bone as a dead tissue. It is a living tissue, and it consists of calcium, phosphate, a lot of minerals. It gives our body its structure so we can walk. It also provides calcium and other minerals to maintain a normal balance in our blood.
LISA CLARK: As a living system, what is the normal bone cycle like? How does that work?
CAROLYN BECKER, MD: The reason we worry about osteoporosis is that bone remodels itself. It is constantly getting rid of the old and replacing it with new bone so that it's structurally sound and strong bone. As we get older, especially after age 30 or 35, for some reason the bone that gets eaten away to be replaced by new bone is not replaced by as much new bone, so there's a net loss of bone over the years. The remodeling process goes on very rapidly after menopause for women, and that's often a time when there is very rapid bone loss.
LISA CLARK: Why does that happen, do they think?
CAROLYN BECKER, MD: We think it's because the lack of estrogen sets up a dynamic within the bone so that the bone starts to be more resorbed, or eaten away, rather than built up. There are two kinds of cells that we find in the bone -- osteoblasts and osteoclasts. Osteoblasts build bone, osteoclasts are like little Pac-Men that eat away the bone and cause these craters to be formed. Lack of estrogen and various other hormonal changes, as well as aging, seem to affect this balance so that the bone cells eating away the bone for some reason overcome the cells that are forming new bone, so you have a loss of bone over time.
Now, there is a bit of an erroneous assumption that osteoporosis is just something that affects older women. Actually, you could say that osteoporosis starts in childhood.
CAROLYN BECKER, MD: There are two concepts. There's a concept of peak bone mass, and there's a concept of bone loss. You can end up with osteoporosis at age 50 if you never built a good skeleton when you were young. I think of the skeleton as a bank account. Until the age of 30 it's all deposit. After age 30 to age 35, it's all withdrawal. So if, for some reason, as a child you did not get enough calcium, you didn't have a healthy lifestyle, you smoked, you didn't have normal periods as a young teenage girl, you will never build a strong skeleton for the rest of your life, and you may start losing bone in your 30s, and you're already at such a low level you could have osteoporosis at age 50, and you'd have the bones of an 80-year-old woman when you're only 50.
LISA CLARK: Now, everyone does lose bone mass as the age after age 35. What is the normal level of bone loss per year for an average person, if there is an average person?
CAROLYN BECKER, MD: There is, and we've studied this over many years. Cohorts of women and men lose bone at the rate of about 0.5 percent to 1 percent per year. It's a very slow rate of bone loss, but after menopause, some women can lose 2 percent to 5 percent of their bone per year, which is a tremendous amount of bone loss.
LISA CLARK: The estrogen loss accelerates this dramatically?
CAROLYN BECKER, MD: Yes, it does.
LISA CLARK: What, then, is osteoporosis from a clinical standpoint? How do you define it?
CAROLYN BECKER, MD: It's a combination of low bone mass -- just not enough bone, porous bone, which is really the definition -- osteoporosis -- and structural or microscopic damage to the bone that's there, so that it really cannot support the weight of the person, and they can have what we call "fragility fractures," meaning they can fracture with minimal or no trauma.
LISA CLARK: And that's often when people first realize they have osteoporosis?
CAROLYN BECKER, MD: Yes. Unfortunately, I've seen many patients who never thought they had osteoporosis, and maybe they were hugged by a grandchild and they cracked their rib, or they were opening a window and crushed one of their vertebrae, and that was the first indication they had that they had osteoporosis.
LISA CLARK: We've talked about lack of adequate nutrition or exercise in youth or estrogen loss as a woman gets older, but there are also medical conditions or drugs that can accelerate or cause osteoporosis effects as well.
CAROLYN BECKER, MD: Yes. We call this "secondary osteoporosis." As endocrinologists, we often look for these causes of osteoporosis when patients come in with severe bone loss. It can be anything including malabsorption, patients with celiac disease or patients with Crohn's or other gastrointestinal problems, patients who are put on steroids or excessive thyroid hormones, patients who have other diseases, malignancies. There are a number of other conditions that can lead to low bone mass and osteoporosis.
LISA CLARK: So the message is, "Be vigilant. Talk to your doctor. Be aware of the risks."
CAROLYN BECKER, MD: Yes, absolutely.
LISA CLARK: And have it checked out.
CAROLYN BECKER, MD: Absolutely.
LISA CLARK: Thank you so much for joining us, Dr. Becker.
CAROLYN BECKER, MD: Thank you. My pleasure.
LISA CLARK: And our thanks to you for joining our webcast. I'm Lisa Clark.