Elderly men and women are at high risk of hip fracture due to bone loss, say researchers, but given rates of bone loss, screening can occur as infrequently as every five years.

Bone loss can lead to osteoporosis, a condition in which the bones become brittle and more prone to fracture.

The study, which tracked 9,423 participants between the ages of 25 and 85, found bone loss among women aged 50 to 54, which data showed had the most pronounced bone loss of all age groups, was 1.3 per cent.

According to the researchers, this decrease is within the margin or error of most bone densitometry machines, meaning that the loss is not as significant as once thought.

"The extent of the bone loss that we observed suggests that repeat measurements of bone density could be delayed to intervals of up to five years in the absence of other risk factors," they write.

All the study's participants lived within 50 km of nine major Canadian cities: St. John's, Halifax, Quebec City, Toronto, Hamilton, Kingston, Saskatoon, Calgary, Vancouver. Their bone density was measured through dual energy x-ray absorptiometry, a test which x-rays different bone structures to determine strength.

Decreases in bone density start as early as 25 in men and 40 in women, the study finds.

Begins at age 25

Bone loss in the lumbar spine, total hip and femoral neck begins at age 25 in men and at age 40 in women, with the rate of decline picking up past age 70 in women and men older than 65.

But bone loss in only the hips can begin as early as age 20, according to the researchers.

The study also looked at the role drugs that prevent bone loss have in halting the decline. These include the bisphosphonates alendronate, risedronate and hormone replacement therapy.

In women who did not take drugs to prevent a loss in bone density, bone loss was much more pronounced than in those taking the drugs.

This occurred even in patients who had a greater degree of bone loss at the beginning of the study than those participants not on medications.

The same trend was seen in men, though fewer men took medications to prevent bone loss in the study.

"We found that use of antiresorptive aganets was associated with a reduction in the rate of bone loss at all skeletal sites among participants aged 50 and older," write the authors.

The study is published Tuesday in the Canadian Medical Association Journal.