London, Jan 30 (IANS) Hip fractures in grandfathers are linked to low bone density and reduced bone size in their grandsons, new research shows.
“This is the first time this risk factor for low bone mass has been demonstrated across two generations,” said Mattias Lorentzon, associate professor at the Sahlgrenska Academy, who led the research team.

“This new risk factor may be significant for the diagnosis of low bone mass and suggests possible mechanisms for the inheritance of low bone mass and fracture risk,” he added.

The study looked at around 3,700 grandparents and their grandsons from a national register, of which 270 grandsons had reduced bone density, or less bone mineral in their skeleton.

All of these also had a grandparent who had broken their hip, as opposed to those who did not have any relatives who had broken a hip and had normal bone health.

“We then divided these men with reduced bone density into two groups,” says Lorentzon. “In the first, we looked at those who had a grandmother who had broken a hip. In the second, we looked at whether a grandfather had suffered a hip fracture.”

It emerged that the men who had a male relative who had suffered a fracture had up to five percent less bone density and four percent smaller bones than those who did not.

Ten percent lower bone density can increase the risk of fractures as much as threefold. The research team also took account other risk factors for osteoporosis, such as smoking, physical activity, calcium intake, age, weight and gender.

“Despite these other risk factors, we could see that bone size is reduced and that this leads to lower bone density, which together means low bone mass - a risk factor for osteoporosis. In other words, they run a greater risk of fractures in the future than their peers,” says Lorentzon.

The finding could lead to improvements in the identification of patients at increased risk of osteoporosis, said a Sahlgrenska release.

The study was published in the Journal of Clinical Endocrinology & Metabolism.