Obesity-linked high blood volumes render PSA prostate cancer test less effective, stud...( M.D. Partins former postdoctoral fellow...),Health

Using records of patients treated for prostate cancer between 1988 and 2006 at The Johns Hopkins Hospital, Duke University and various Veterans Affairs hospitals, Partin, Freedland and their colleagues compiled information on PSA concentration and body mass index (BMI), a ratio of body weight to height that generally indicates whether someone is underweight, normal weight or overweight.

Using a standard calculation, the researchers used BMIs to estimate the amount of blood circulating in each patients body. A different calculation used this blood volume, along with PSA concentrations, to estimate the total amount of PSA each patient had.

As expected, PSA concentrations were typically lower in the obese patients than in the normal-weight ones, although the total amount of PSA was about the same in both groups of patients.

Its clear to us that excess blood had diluted PSA concentrations in that group, says Partin.

Freedland says a variety of new tests currently in development for cancer and other diseases rely on the concentrations of disease markers similar to PSA circulating in the blood. For these other tests just starting down the development pipeline, he says, we need to think about the actual total amount of a biological marker rather than concentration.

'/>"/>