Looking for osteoporosis in spit. (Biology).

Roger B. Johnson, a dentist, suspected that he and his colleagues could routinely check their patients for chronic diseases when they come in for teeth cleanings and check-ups. Because gum disease offers one indicator of weakening bone, or osteoporosis, Johnson wondered if there are other oral markers of the disease. He now reports finding three compounds in saliva that could serve as the basis for gauging bone loss.

Working with Johnson on a yearlong study, veterinarians removed the ovaries of six adult ewes to mimic menopause in women, whose hormone changes can foster bone loss. At 4-month intervals, Johnson's team at the University of Mississippi Medical Center in Jackson sampled saliva, blood, and urine from these animals and from another half dozen ewes with intact ovaries. At the end of a year, all of the animals were slaughtered and the researchers made precise density measurements of quarter-inch-thick slices of the animals' leg bones.

Compared with the intact ewes, those without ovaries had about 10 percent less bone density after the year. During this time, the sheep with simulated menopause also exhibited a gradual increase in a marker of bone loss and in blood concentrations of interleukin-6, a sign of hormone-driven bone loss. Blood concentrations of osteocalcin, which signals reduced bone production, also fell during the study. The amounts of these biomarkers fluctuated normally in the animals with ovaries.

These changes in the urine and blood were mirrored in saliva.

Johnson's group has now begun validating saliva tests for the biomarkers in people, starting with eight patients receiving hip implants. The researchers measured the biomarkers in these patients' saliva and correlated the results with the density of bone fragments removed during surgery. These early data show some correspondence with the sheep data and bolster Johnson's hope that saliva can be used "to screen for osteoporosis."--J.R.