Aug. 20, 2012 -- New evidence that links low levels of lead in the blood to an increased risk of gout suggests that currently acceptable levels of lead exposure are too high.
In a study published in Annals of Internal Medicine, researchers report that the risk of gout is apparently elevated even among adults whose blood lead levels are several times less than what the CDC considers acceptable.
“The point here is that there is no such thing as a safe lead level,” says researcher Eswar Krishnan, MD, an assistant professor at Stanford University School of Medicine.
Gout is a painful form of arthritis that's often related to a buildup of uric acid in joints, a condition called hyperuricemia. Obesity, diabetes, and hypertension are known risk factors for gout.
But, Krishnan tells WebMD, such risk factors cannot explain every case. So he went looking for others. A review of the medical literature pointed him toward lead.
Krishnan says it's been known for some time that lead in the blood at concentrations greater than 80 micrograms per deciliter (mcg/dL), or eight times the acceptable level, is associated with hyperuricemia and gout. But he says that his own findings concerning much lower levels were unexpected.
"I honestly was expecting a negative result or an unimpressive one," he says. "What we found was very surprising."
For the study, Krishnan and his colleagues used data from two recent National Health and Nutrition Examination Surveys, which are conducted annually by the CDC. They focused on men and women over the age of 40 who had no kidney disease. In all, they examined the records of more than 6,000 adults from around the United States.
While most adults have blood lead levels below 10 mcg/dL -- the acceptable level supported by the CDC -- the researchers found that people with blood lead levels as low as 1.2 mcg/dL seemed to have an increased risk of gout.
The risk remained after they adjusted the data to account for differences in age, gender, race, diet, and a variety of health measures. In the study, those with the highest level of lead measured about 4 mcg/dL. Their risk appeared to be about three-and-a-half times that of those with the lowest levels of lead in their blood.
The risk of hyperuricemia -- a common forerunner of gout -- also rose significantly.
Although this study could not prove cause and effect, the research methods were able to uncover the strong link between lead and gout.
More Research Needed on Both Risk and Treatments
Ashwini Sehgal, MD, who wrote an editorial that accompanies Krishnan's study, also found the results surprising. And, like Krishnan, he says more research needs to be done before we fully understand the risks and what to do about them.