ADOLESCENTS with isolated microscopic haematuria should be followed long term after research showed young adults with this finding are much more likely to develop end-stage renal disease, an Australian renal physician says.

Using medical records from more than 1.2 million Israelis aged 16 to 25 years, researchers found that persistent, asymptomatic isolated microscopic haematuria was present in 0.3% of the population, and was twice as common in males as in females. (1)

Over a follow-up period of 22 years, end-stage renal disease (ESRD) developed in 26 participants (0.7%) with haematuria, and 539 (0.045%) without, yielding a crude hazard ratio of 19.5.

After adjusting for confounders such as age, body mass index and blood pressure, a multivariate model yielded a very similar hazard ratio of 18.5.

The research, published in JAMA, found that the primary aetiology for the ESRD was glomerular disease.

“Our findings suggest that persistent asymptomatic isolated microscopic haematuria detected during adolescence and young adulthood is an early marker for primary glomerular injury and may be the first sign of an occult renal disease”, the researchers wrote.

Dr Tim Mathew, medical director of Kidney Health Australia, said the research made an important contribution to understanding the best way to manage isolated haematuria in young people.

Dr Mathew said although there was consensus that haematuria should be investigated once immediate sinister causes had been ruled out, the management of isolated haematuria was more contentious.

“The question is, do you follow them up or do you discharge them? I think this paper tilts the scales in the direction of justifying long-term follow-up, to be able to intervene should proteinuria develop or should their kidney function begin to deteriorate.”

The JAMA research also raised some debate about whether screening young adults for microscopic haematuria was justified.

A related editorial said that screening could be used to detect chronic kidney disease early. (2)

“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”, the editorial said.

The US Preventive Services Task Force is currently considering the introduction of chronic kidney disease screening.

However Professor Jonathan Craig, professor of clinical epidemiology at the University of Sydney, said the editorial’s suggestion to introduce screening was not justified.

“It’s a very, very long bow and problematic for a number of reasons”, said Professor Craig, who has a research focus on screening.

He said there was no indication that early detection would lead to effective therapy, which was the standard criterion for screening programs, and the absolute risk reduction for ESRD would be very low.

“What therapy for microscopic haematuria is being considered? What evidence is there for effective therapy? What evidence is there for screen-detected therapy? What about the harms of testing, such as kidney biopsies?”

Dr Mathew said moves away from the use of dipstick testing to screen for renal pathology would mean that incidental haematuria was detected less often in young people.

“There’s an increasing tendency to use urine ACR [albumin:creatinine ratio] as the method of urinalysis which preclude the option of finding blood”, he said

– Sophie McNamara

1. JAMA 2011; 306: 729-736

2. JAMA 2011; 306: 764-765

Posted 22 August 2011

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