Strengthening Brittle Bones

One of the most universal symptoms of aging--unlike shrinking stature or wrinkling skin--is hidden from view. Virtually all bones in the body tend to become brittle because they lose some of the calcium compounds that provide rigidity and strength. The elderly are notoriously vulnerable to hip fractures from even a light fall. In some cases, ribs or the long bones of the arms or legs fracture spontaneously, without a fall or noticeable trauma. The condition can also be congenital, and in such rare cases it becomes a lifelong affliction.

At first glance, the remedy for what is technically called osteoporosis (porousness of bone) seems obvious: feed the patient more calcium-rich food. This does not work, however, because in these patients calcium is poorly absorbed from food. Now, a team of researchers headed by Dr. Frederic C. Bartter of the National Heart and Lung Institute in Bethesda, Md., has devised a promising treatment based upon adding calcium via the bloodstream.

The calcium in bones is not an inert, permanent part of their structure, like steel beams in a building. Rather, it is continuously being removed and replaced by the body's normal metabolic processes. So osteoporosis can result from too much calcium being removed too fast, too little being replaced too slowly, or both.

The Bartter team started with two known facts. Parathyroid hormone, secreted by the thyroid's tiny satellite glands, directs the removal of calcium from bone and its release into the blood. One of the thyroid's own hormones, thyrocalcitonin, controls the converse--the transfer of calcium from blood to bone. These two hormones balance each other in normal metabolism by an exquisitely delicate feedback mechanism. Too little calcium in the blood signals the parathyroids to take some out of the bones and put it into circulation; a sufficiency of calcium in the blood induces a stop order from the thyroid.

Surprise Bonus. Bartter and his colleagues reasoned that if they could boost the blood's calcium content safely, the effect would be to slow down the loss of calcium from bone. They chose a compound containing calcium gluconate and infused it into the patients' veins. They settled on a dose of 1 gram (1/30 oz.) for a 145-lb. man and took four hours to administer it to avoid overstimulating the heart. The infusions were given twelve times, a day or two apart.

Not only did nine of the first twelve patients report relief from pain and regain their ability to move about and lift objects without suffering fractures, but there was also a bonus that Dr. Bartter had scarcely dared to hope for. The treatment's effect lasted for months, and in one case for more than two years. If the effect wears off, Bartter says, the infusions can be easily and safely repeated. While no one yet claims to know what 'makes nature's calcium-regulating mechanism go wrong, medical science now has a way to put it right.

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