A new study has found a link between hip fractures in grandfathers and low bone density and reduced bone size in their grandsons.
According to lead researcher Mattias Lorentzon, the new risk factor may be significant for diagnosis of low bone mass and suggests possible mechanisms for the inheritance of low bone mass and fracture risk.
"This is the first time this risk factor for low bone mass has been demonstrated across two generations," said Lorentzon.
For the study, researchers looked at 3,700 grandparents and their grandsons.
They found 270 of these grandsons had reduced bone density, in other words less bone mineral in their skeleton.
They 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," said 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," Lorentzon added.
The study revealed that men who had a male relative who had suffered a fracture had up to 5pct less bone density and 4pct smaller bones than those who did not.
By way of comparison, 10pct less bone density can increase the risk of fractures as much as threefold.
"Despite 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," Lorentzon added.
This finding could lead to improvements in the identification of patients at increased risk of osteoporosis.
The study is published in the Journal of Clinical Endocrinology and Metabolism.