Osteoporosis
Francis A. Greenspan, MD
Chief, Thyroid Clinic, Member Division of Endocrinology and the
Department of Endocrinology
University of California, San Francisco
Osteoporosis is a disease characterized by a reduction in the
amount of bone in your skeleton as well as deterioration of bone
structure. The result is an increase in your risk for fractures.
Osteoporosis affects 4 to 6 million post menopausal Caucasian women.
Approximately half of all Caucasian women will experience an osteoporotic
fracture during their lifetime. In the United States there are approximately
1.5 million osteoporotic fractures every year. Women tend to develop
osteoporosis at a rate higher than men primarily because of accelerated
bone loss that occurs after menopause. Men have a lower risk, but
their lifetime risk for osteoporosis is still 25% for a 60 year
old man.
Patients who have had either hyperthyroidism or thyroid cancer
are at increased risk for osteoporosis. Those with a history of
hyperthyroidism may have lost bone during their period of increased
thyroid activity. Most patients with thyroid cancer are maintained
in a mildly hyperthyroid state to try to decrease the likelihood
of cancer recurrence by suppressing thyroid stimulating hormone
(TSH) from your pituitary gland. This increases the risk of osteoporosis.
The diagnosis of osteoporosis is made by a bone density test, commonly
measuring the bone density of your spine and or hip.
Treatment
The first approach to treating osteoporosis is the reduction of
factors that may increase your risk for the problem. This may include
eliminating smoking and alcohol abuse, as well as, adding physical
conditioning to reduce your risk of falling. Total calcium intake
from diet and supplements should be 1200 to 1500 milligrams per
day. A daily intake of 400 IU of vitamin D or up to 800 IUs in those
over 65 will help maintain healthy bones.
Estrogen used to be given to women after menopause. Although this
reduced of osteoporosis developing, it had the unfortunate side
effect of increasing the risk for heart disease and breast cancer.
Although very effective for short-term use, these medications are
no longer recommended for long term treatment.
Calcitonin was one of the first medications shown to be a potent
inhibitor of bone breakdown. It is given in a nasal spray and has
few side effects. Unfortunately, careful studies have not shown
significant in vertebral fractures in individuals taking Calcitonin
compared to those who don’t.
Bi-phosphonates are a class compounds developed for industrial
use to inhibit the growth of crystals. They were soon discovered
to have a number of biological effects, including the ability to
inhibit bone breakdown. Aledronate (Fosamax) was the first of this
class of drugs available for the treatment of osteoporosis. Those
who have been able to take aledronate have achieved significant
increase in bone density (mean 7%-9% at the spine and 5%-8% at the
hip) compared to placebo.
The bi-phosphonates must be taken on an empty stomach first thing
in the morning with water only and cannot be followed by any food
nor drink for at least 30 minutes. Unfortunately they may cause
inflammation of the stomach (gastritis) and esophagus (esophagitis)
in some patients. Medications to reduce these intestinal effects
and control stomach acid will help. These drugs include Ranitidene,
Pepcid, Protonics, Prilosec, and Nexium. It’s also possible
to take the medicine only once a week, which appears to reduce the
frequency and severity of intestinal problems.
Actonel is another bi-phosphonate that works in the same manner
as aledronate, reducing the risk of fracture by increasing bone
density. In one study Actonel reduced the risk of spine fractures
by approximately 40% at 3 years. In another study there was a reduction
in the incidence of hip fracture of approximately 40% by the third
year of treatment.
Parathyroid hormone regulates calcium balance through a mechanism
completely different from that of estrogen, Calcitonin, or bi-phosphonates.
It not only increases bone mass but also seems to restore bone architecture.
Unfortunately it has to be given by injection daily. It seems to
be better than all other approaches to increasing bone density and
reducing fracture risk. Studies in progress may show it to be a
valuable addition to the treatment of osteoporosis either alone
or in combination with drugs that prevent bone resorption, but long
term data, including toxcity and not yet available.
In summary, your doctor has a variety of treatments available for
osteoporosis. If that is your problem, you can expect your physician
to either discuss these alternatives at the time your treatment
is planned or to refer you to an endocrinologist who specializes
in bone disease to guide you to the medication that is best for
you.
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