NEW YORK (Reuters Health) — Men and women who have a broken foot that cannot be traced to an obvious cause may be showing the first signs of the bone-thinning disease osteoporosis, according to researchers at the Ohio State University in Columbus.

Of 21 patients who went to the doctor with unexplained fractures in the metatarsals — the relatively long bones in the middle of the foot — 20 turned out to have signs of bone loss indicating osteoporosis.

“Each foot fracture had been caused by normal weight bearing — some patients were walking when they felt their bones break,” said study co-author Dr. Rodney Tomczak in a statement issued by the University. While the stress of running or exercising can cause a broken foot bone, as can a blow to the foot, none of the patients had any obvious cause of the fracture.

Tomczak and colleague Dr. Robert VanCourt reported their findings recently at the annual meeting of the American College of Foot and Ankle Surgeons.

The patients included six men, aged 19 to 55, and 15 women, aged 40 to 72. Four were African American and the rest Caucasian. All six men had signs of osteoporosis.

“That was a startling find,” Tomczak said. “Men usually don’t suffer from osteoporosis.” He noted that all of the men and 12 of the women had other conditions that might contribute to the development of osteoporosis, such as diabetes, kidney failure, menopause, low testosterone levels or thyroid problems.

Bone density scans indicated that 9 of the patients had osteoporosis, and 10 had significant bone loss likely to develop into the condition. Weight was not related to the risk of fracture.

“Based on a very high correlation of patients with insufficiency fractures to low bone mineral mass in this study, patients who present with unexplained metatarsal fractures, including men, should be referred for bone density testing,” the authors concluded.

In addition, Tomczak and VanCourt recommended that “the public awareness campaign concerning osteoporosis should be refocused to include men, who may also be suffering from this disease.”

The researchers noted that about 22 million North Americans have osteoporosis, and about 1.5 million of these will suffer at least one bone fracture in a given year. Although this condition is usually thought to affect elderly women, the average age of women in this study was 54, and the average age of the men was 35.