Persistent, microscopic blood in urine associated with increased risk of kidney disease

"Persistent asymptomatic isolated microscopic hematuria is a frequent incidental finding on routine examination of children, adolescents, and young adults. The most recent American Academy of Pediatrics guidelines rescinded the recommendation for urine screening during the second decade of life," according to background information in the article. "Microscopic hematuria can be either an isolated finding accompanied by other kidney abnormalities or part of a systemic condition. It also can be transient or persistent." Few data are available on long-term outcomes among adolescents and young adults with persistent asymptomatic isolated microscopic hematuria.

Asaf Vivante, M.D., of the Edmond and Lily Safra Children's Hospital, Tel Hashomer, Israel, and colleagues conducted a nationwide, population-based study in Israel to evaluate the risk of treated end-stage renal disease (ESRD) in adolescents and young adults with persistent asymptomatic isolated microscopic hematuria. The study included medical data from 1,203,626 persons aged 16 through 25 years (60 percent male) who were examined for fitness for military service between 1975 and 1997 and who were linked to the Israeli treated ESRD registry. Incident cases of treated ESRD from January 1980 to May 2010 were included.

Persistent asymptomatic isolated microscopic hematuria was diagnosed in 3,690 of the 1,203,626 eligible individuals (0.3 percent). The condition at enrollment was twice as prevalent among male as female participants (0.4 percent and 0.2 percent). During 21.9 years of follow-up, treated ESRD developed in 26 individuals (0.70 percent) with and 539 (0.045 percent) without persistent asymptomatic isolated microscopic hematuria. A multivariate model adjusted for age, sex, paternal country of origin, year of enrollment, body mass index, and blood pressure at baseline revealed a significantly increased risk of developing ESRD associated with persistent asymptomatic isolated microscopic hematuria. However, the researchers note that the incidence and absolute risk of ESRD were quite low.

"A substantially increased risk for treated ESRD attributed to primary glomerular disease was found for individuals with persistent asymptomatic isolated microscopic hematuria compared with those without the condition. The fraction of treated ESRD attributed to microscopic hematuria was 4.3 percent," the authors write.

"… demonstrating that persistent isolated microscopic hematuria is a risk marker for ESRD highlights the importance of early detection of pre-dialysis chronic kidney disease for the application of current and future strategies to slow the deterioration to ESRD. It also shows the importance of considering complications and comorbid conditions across the range of chronic kidney disease."

"In light of our findings, future studies are warranted to evaluate the utility of population screening in improving clinical outcomes," the researchers conclude.

Editorial: Has the Time Come to Include Urine Dipstick Testing in Screening Asymptomatic Young Adults?

In an accompanying editorial, Robert S. Brown, M.D., of Beth Israel Deaconess Medical Center, Boston, writes that "in the United States, because the prevalence of chronic kidney disease (CKD) is estimated to be from 70- to 200-fold greater than the prevalence of treated ESRD, perhaps an argument could be made for the inclusion of [urine] dipstick testing for hematuria as part of routine screening of young adults."

"The early identification of persons at risk for CKD also should promote other healthy interventions for smoking, hypercholesterolemia, glycemic control, and reduction of sodium intake. The U.S. Preventive Services Task Force has no current recommendation for CKD screening, but the topic is under consideration."

"… it appears that the time may have arrived for routine urine dipstick screening in adolescents and adults, at least at all initial examinations and perhaps every 5 to 10 years thereafter," Dr. Brown writes.