Diet and Microalbuminuria
Dr. Bakris: Right. That is an important point. The 15-year follow-up study of CARDIA was just published online in the American Journal of Kidney Diseases. CARDIA was a huge cardiovascular risk factor study that looked at development of microalbuminuria and factors that predicted it. It turns out that poor diet and with that, obesity, was by far the highest risk factor for developing microalbuminuria.
To be specific, before everybody blames McDonald's, Wendy's, and everybody else, it was not fast-food consumption, but a generally poor diet. It was the antithesis of DASH. People who did not have a good fruit and vegetable intake, people who had gained weight, who were obese, who had a lot of sugars in their diets -- those are the people who developed microalbuminuria. Those dietary factors are consistent with vascular inflammation. I realize I just sprung it on you before we went on the air this morning, but what are your thoughts on that? It really calls into question the whole issue of microalbuminuria, any single value, as a predictor itself.
Dr. Glassock: I look forward to reading the paper, George. I would agree that a lot of environmental influences can alter albumin excretion. Smoking is one. Probably environmental pollution is another, because in highly polluted areas we see a much higher prevalence of microalbuminuria. Of course, obesity and remote inflammation of any cause can increase albumin excretion. Many things have to be taken into account when examining the relationship between albuminuria and kidney disease, because many factors are completely external to the kidneys.
Dr. Bakris: Right. I think the take-home message as far as microalbuminuria and the kidneys goes is that it is important to measure it. It is important to look at the trajectory, however, and not at an absolute value in the face of the environment and treatment that's being given. If the albumin level is going up and everything else appears to be controlled, then there probably is a real problem. Otherwise, it is something you should probably measure once a year, which is what the guideline says.
Dr. Glassock: That's correct. The fact that albumin excretion tracks so tightly with these other risk factors, such as smoking, obesity, and environmental pollution, makes it very difficult to determine whether an approach to microalbuminuria itself can influence outcomes independent of altering these risk factors, which we already know contribute significantly to cardiovascular morbidity and mortality.
Dr. Bakris: That is exactly right, and is the reason the FDA isn't giving it any credence.