Las Vegas, NV - Having too much uric acid in the blood may weaken older men's bones, new findings presented here at the National Kidney Foundation's 2014 Spring Clinical Meetings suggest.
Men 65 and older with higher-than-normal uric acid levels were 62 percent more likely to fracture a hip, Tapan Mehta, MD, at the University of Colorado-Denver, and his colleagues found. "High uric acid levels appear to be associated with a higher rate of hip fractures in older men," Dr. Mehta said. "We were not able to find a relationship between uric acid and hip fractures in women, suggesting that other factors are more important in women."
Uric acid is a normal byproduct of the breakdown of cells within the body. Eating certain foods, including sugar and animal products, boosts uric acid levels, making it more difficult for the kidneys to clear uric acid from the blood. "People with unhealthy dietary habits are more likely to have high uric acid levels," Dr. Mehta said. "And people with kidney disease are more likely to have high uric acid levels."
High uric acid levels are known to increase the risk of gout and kidney stones, and recent research suggests they can also contribute to high blood pressure, heart disease and kidney disease. To investigate whether uric acid levels might also be associated with bone health, Dr. Mehta and his team looked at data from the Cardiovascular Health Study on 4,692 men and women who had their baseline uric acid levels recorded.
Among the 1,963 men in the study, 430 had uric acid levels above 7 mg/dL (normal range is 3.5-7.2). Men with higher uric acid levels were more likely to be obese and in poor health. During follow-up, which lasted approximately 11 years, 156 hip fractures occurred.
"There are several possible mechanisms that might be involved," Dr. Mehta said. "High uric acid levels may impair nitric oxide availability in the bone and this may increase bone fragility and fracture risk. Uric acid may also induce inflammation in the bone, and this could lead to more fragile bone. In addition, uric acid suppresses vitamin D activation and this could play a role in the higher risk of fractures. But further studies are needed to better understand the mechanism of this association."
"There have been a number of recent studies showing an association between elevated uric acid and several negative outcomes including more rapid progression of kidney disease," said Thomas Manley, director of scientific activities at the National Kidney Foundation. "Most clinical practice guidelines suggest that more evidence is needed before they would recommend screening for or treating elevated uric acid levels, except in the presence of symptoms of gout to reduce those symptoms."
"However, there are clinical studies now underway evaluating whether lowering uric acid may be beneficial even in the absence of symptoms," Manley added. "This has the potential to be a new therapeutic option to improve outcomes for kidney disease patients as several of these studies are looking at how treating elevated uric acid impacts the progression of kidney disease."
The National Kidney Foundation is the leading organization in the U.S. dedicated to the awareness, prevention and treatment of kidney disease for hundreds of thousands of healthcare professionals, millions of patients and their families, and tens of millions of Americans at risk. For more information, visit www.kidney.org.