Hormone Replacement and Osteoporosis (cont.)
Coburn Hobar, MD
Jessica B Johnson
Kristine M Lohr, MD
Mary L Windle, PharmD
Lee P Shulman, MD
IN THIS ARTICLE
Menopause and Osteoporosis
Menopause occurs when reproductive hormone levels have dropped enough to cause menstruation to stop. In most women, menopause happens between the ages of 48 and 53 years. Many women experience early signs of menopause, or perimenopause, beginning at around age 45.
Surgical menopause occurs when a woman undergoes a complete hysterectomy, which is surgery to remove the uterus and ovaries, or an oophorectomy, which is surgery to remove the ovaries alone. Some of the conditions that cause a woman to have a complete (or total) hysterectomy or an oophorectomy include severe endometriosis, uterine or ovarian cancer, or persistent uterine fibroids. Regardless of whether a woman has a complete hysterectomy or an oophorectomy, the absence of the estrogen-producing ovaries causes menopause. Surgical menopause can occur in women at any age if they undergo a procedure to remove the ovaries.
Chemical menopause occurs when women undergoing chemotherapy or radiation treatment for certain kinds of cancer or other conditions experience menopause. In some cases, chemical menopause reverses and the body will begin producing premenopausal amounts of estrogen once more.
Although some women experience the typical symptoms of menopause, other women experience more significant symptoms and others pass through menopause without much discomfort. Menopausal symptoms include:
Bone is made mostly of collagen, which is a protein that is woven into a flexible framework, and calcium phosphate and calcium carbonate, which are minerals that add strength and harden the framework. Even though it is mostly made of protein and minerals, bone is living growing tissue. Throughout the lifetime, old bone is broken down (a process called resorption) and new bone is added to the skeleton (formation). When more bone is broken down than is deposited, bone loss is occurring (see Prevention of Osteoporosis and What is Bone Loss? for information on factors leading to bone loss).
Bone is added fastest during childhood and teenage years. As a result, bones become larger, heavier, and stronger (denser). Bone formation continues until the peak bone mass (maximum solidness and strength) is reached. Peak bone mass (or bone density) is reached around age 30. After age 30, bone resorption slowly begins to exceed bone formation. This leads to bone loss. Bone loss in women occurs fastest in the first few years after menopause, but bone loss continues into old age.
Bone loss occurs fastest during and after menopause because the rate of bone loss increases as a woman’s body stops producing estrogen, which occurs during menopause. Estrogen (a reproductive hormone) is important for bone growth and strength because it works with the cells responsible for forming bone (called osteoblasts). Estrogen works with these cells to stimulate the substances in the body that encourage bone growth. The end result is that as estrogen levels decrease in menopause, the substances in the body that cause bone to be built decrease. Consequently, bone is formed more slowly. Whenever bone is broken down faster than it is formed, bone loss occurs and can eventually lead to low bone density (osteopenia) and osteoporosis.
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