The AUA guidelines for microhematuria are broad because there’s little known about how best to determine who needs costly evaluations. Now, a study suggests urologists will be able to use the degree of microhematuria and the number of positive samples to determine whether patients should get further workups.
“Our data is proof our patients have identifiable characteristics that put them at higher risk for kidney/bladder cancer or stone disease. Our goal is to provide better evidence about who should have further diagnostic testing, which includes imaging and cystoscopy,” said lead author Richard Matulewicz, MD, MS, of McGaw Medical Center of Northwestern University, Chicago.
At issue: How should urologists evaluate microhematuria?
“Though the definition of abnormal microhematuria has changed over the years, past health screening studies have estimated that between 2% and 30% of adults have microhematuria. Higher rates are seen in older people and smokers. Urologists see many of these patients, and very few have a urologic condition,” Dr. Matulewicz told Urology Times.
However, AUA guidelines suggest that adult patients undergo evaluations when microhematuria—three or more red blood cells on a single urinalysis—occurs without an obvious benign etiology like a urinary tract infection or trauma, said co-author Joshua Meeks, MD, PhD, of Northwestern University Feinberg School of Medicine, Chicago.
“The AUA microhematuria guidelines are broad because they are based on the best evidence currently available,” Dr. Meeks told Urology Times. “For example, to date there has not been a minimum number of red cells that are most predictive of identifying bladder cancer.”
In the new study, presented at the AUA annual meeting in San Diego, the authors examined a hospital system database of 11,902 patients with a new diagnosis of microhematuria from 2008-2011.
The patients were 71% female, 48% Caucasian, 22% African-American, 4% Hispanic, 3% Asian, and 22% unknown. They were followed indefinitely—a median of 5.8 years—for diagnosis of bladder cancer, kidney cancer, and urolithiasis.
Sixty-one percent of patients had an initial urinalysis of 3-10 RBC/hpf, and 10,254 (35.2%) had at least one more urinalysis in the 6 months after initial diagnosis.