Parathyroid surgery proves its worth.

Tiny glands that go into a frenzy of hormone production can cause kidney disease and bone damage. Because these overactive parathyroid glands often produce no overt symptoms, however, doctors are frequently unsure whether to remove them surgically. A new study indicates that this operation can provide long-term benefits even for patients with no apparent problems.

As small as peppercorns, the four parathyroid glands in the neck nevertheless pack a big punch. The hormone they make regulates blood concentrations of calcium, which is crucial to basic metabolic functions.

In 15 to 25 people per 100,000, at least one of the glands is hyperactive, usually due to a benign tumor. The flood of hormones that results can silently drain calcium from bones, inflate its concentration in the blood, and dump it into the urine.

In the new study, doctors at Columbia University College of Physicians and Surgeons in New York identified 121 people with elevated blood-calcium concentrations, indicating hyperactive parathyroids. Of these, 61 had opted for surgery to remove their parathyroids while 60 had not. Several people in each group had obvious symptoms, usually a history of kidney stones, but most showed no outward signs of disease.

After tracking all the patients for a decade, the scientists report that surgery provided relief from several problems. For example, 12 patients had had kidney stones before surgery, but none of them did during the 10 years afterward, the scientists report in the Oct. 21 NEW ENGLAND JOURNAL OF MEDICINE (NEJM). Among the nonsurgery group, 8 had had kidney stones before the study began, and 6 of these people experienced a recurrence during the study.

In the decade after their surgery, patients averaged bone density gains of 12 percent in vertebrae and 14 percent in hip bones, says study coauthor Shonni J. Silverberg, an endocrinologist at Columbia. Average bone density in those who avoided surgery stayed about the same.

Among these nonsurgical participants, however, 11 did lose bone mass. Five of these were women who entered menopause during the study. Fourteen of the 60 people not getting surgery showed other signs of worsening hyperparathyroidism.

In 1990, the National Institutes of Health set guidelines for surgery in patients with this parathyroid condition. One criterion is moderately high calcium concentrations in the blood. However, many people refuse an operation if they have no overt symptoms, and doctors often hesitate to recommend it.

"The basic philosophy was, if we didn't know a patient would be significantly helped, we didn't call for [surgery]," says Michael A. Levine, an endocrinologist at Johns Hopkins Medical Institutions in Baltimore.

That may now change, he says, since the study indicates clearly that many people add bone mass after surgery. "This is an important study," Levine says, predicting that NIH will revise its guidelines.

Meanwhile, nuclear imaging has helped doctors pinpoint which parathyroid gland is diseased, reducing the need for exploratory surgery. As a result, patients undergoing such operations need only a minimal hospital stay, Levine says.

Also, doctors can now monitor parathyroid hormone concentration in the blood during surgery. A prompt fall-off of hormone signifies that the gland removed was the culprit.

Such advances "make surgical treatment simpler and faster than in the past," says NEJM endocrinologist Robert D. Utiger in an editorial in the same journal issue. Those gains and the new findings indicate that surgery "should now be recommended for nearly all patients," he says.