Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, August 23, 1994 TAG: 9408240022
SECTION: EXTRA PAGE: 6 EDITION: METRO
SOURCE: Jane Brody
DATELINE: LENGTH: Long
Bone specialists have identified insufficient calcium in the diet, lack of exercise, cigarette smoking and a natural hormonal decline at menopause as major contributors to the weakened, fragile bones of osteoporosis, a bone-wasting disease that has become a costly epidemic in late 20th-century America.
But through it all, one important contributor to osteoporosis has been largely overlooked: the role played by medications that have bone loss as a major side effect.
In a new booklet, the National Osteoporosis Foundation calls attention to this unfortunate effect of many important medications, not to frighten those who must take them but to suggest that adjustments in treatment or greater attention to prevention might help protect the bones while accomplishing the desired therapeutic goal.
The foundation, based in Washington, repeatedly cautions patients against making unsupervised changes in their medications, lest they endanger their health. A patient should always consult the physician first to determine what changes in treatment are possible, if any, and to monitor the effects of such changes.
Although glucocorticoids are one of the most useful and widely prescribed class of drugs, they are major offenders when it comes to bones. Glucocorticoids, introduced in the late 1940s, are synthetic versions of the steroids produced by the adrenal glands.
About 50 million Americans have conditions that are often treated with glucocorticoids, like arthritis, asthma, allergies, ulcerative colitis, liver disease, lupus, cancer and organ transplants. The drugs, which can be life-enhancing or lifesaving, include cortisone and hydrocortisone, prednisone and prednisolone, triamcinolone, methylprednisolone, dexamethasone, betamethasone, flunisolide and beclomethasone dipropionate.
They act on the immune system, suppressing inflammation and runaway immune responses, like the ones that occur in allergies and autoimmune diseases.
The drugs are often life-sustaining for transplant patients, who might otherwise reject their new organs, and they are important components of cancer chemotherapy. Even when the disease is not immediately life-threatening, the drugs can have a positive effect on the quality of the person's life, especially for those with rheumatoid arthritis, colitis, lupus or multiple sclerosis.
However, they can also interfere with the absorption of dietary calcium, stimulate the action of bone-destroying cells called osteoclasts and inhibit the action of bone-building cells called osteoblasts.
Furthermore, they increase the loss of calcium through the kidneys, which prompts parathyroid hormone to remove calcium from bone to restore the normal blood levels of calcium, an essential mineral.
In children, glucocorticoids can inhibit skeletal growth and development; in adults, they can cause rapid, severe bone loss. In high doses they can result in fractures after just one year of therapy.
Dr. Lawrence G. Raisz, an endocrinologist at the University of Connecticut Health Center and one of the authors of the foundation's booklet, points out that prolonged oral administration of these steroids causes the most damage.
To minimize it, he suggests that they be taken by inhalation or injection and that they be used at the lowest dose and for the shortest time needed. If possible, the drug should be administered intermittently and its use gradually discontinued when the patient's condition improves.
Another of the most commonly prescribed medications in this country is thyroid hormone, which is sold, for example, under the brand name Synthroid, produced by Boots Laboratories. It is given to people whose own thyroid glands are not sufficiently active. When administered at high doses, or when the thyroid gland produces too much hormone, thyroid hormone can cause bone loss.
In a study published last spring in the Journal of the American Medical Association, a California research team documented serious bone loss in the wrists and hips of postmenopausal women taking relatively high doses of thyroid hormone
The researchers, from the University of California-San Diego at La Jolla, also showed that the use of estrogen replacement therapy helped protect the bones of women taking thyroid hormone.
The National Osteoporosis Foundation suggests the annual use of a new test for thyroid stimulating hormone, called TSH, to find out if the right dose of thyroid hormone is being taken because a person's need for the medication can vary over the years.
Phenytoin and barbiturate anticonvulsants, like Dilantin, that are used to control epileptic seizures and certain heart irregularities can also cause osteoporosis. Sometimes alternative medications can be prescribed, particularly for those who are already at high risk for developing osteoporosis.
In most cases, Raisz said, proper attention to nutrition and other bone-sparing habits can negate the ill effects of anticonvulsants on bone.
When large amounts of aluminum-containing antacids are taken to treat gastrointestinal distress, the aluminum can replace calcium in the bones, weakening them.
That is especially a problem in people with poor kidney function. The foundation urges that these over-the-counter medications, like Maalox, Rolaids, Gelusil and Gaviscon, be used in the smallest possible amounts or that another remedy, perhaps one prescribed by a physician, be substituted. Dr. Raisz suggests switching to antacids that do not contain aluminum, like Tums or Alka-Seltzer.
Methotrexate is a potent drug used against a variety of conditions, including many cancers, immune disorders and hard-to-treat arthritic conditions like psoriatic arthritis.
However, it has toxic effects on the cells that form new bone, and it can disrupt kidney function, resulting in the increased excretion of calcium in the urine. Bone loss can also result from long-term use of cyclosporin A, which is used to suppress the rejection of organ transplants as well as to treat certain immune disorders.
Gonadotropin-releasing hormone analogues, often used to treat endometriosis, an overgrowth of uterine tissue, have also been associated with bone loss, particularly in those with low bone mass to start with. And cholestyramine, a drug commonly used to lower cholesterol levels, may impair calcium absorption indirectly by interfering with vitamin D absorption.
Minimizing the risk
In addition to the measures already mentioned, the impact of drugs on bone loss can be countered through measures like the use of hormone replacement therapy, giving estrogen to postmenopausal women and testosterone to men with low levels of this hormone; the use of calcitonin, a bone-sparing alternative to estrogen; the adequate intake of calcium and sufficient vitamin D, from the diet and exposure to sunlight, and a regular program of weight-bearing physical exercise and strength training.
Another way to conserve bone is to refrain from smoking and to consume alcohol and coffee only in moderation.
by CNB