Trace amounts of blood cells in the urine without symptoms is often dismissed, but a study just published in JAMA (The Journal of the American Medical Association) offers evidence that asymptomatic microscopic hematuria can be a risk factor for serious kidney disease requiring dialysis and/or transplant. The authors set out to…

“…evaluate the risk of end-stage renal disease (ESRD) in adolescents and young adults with persistent asymptomatic isolated microscopic hematuria.”

They conducted a cohort study using medical data from 1,203,626 subjects, male and female, who were examined for for the Israeli military services, with reference to the Israeli treated ESRD registry. They were then able to estimate the hazard ratio (HR) of treated ESRD among those diagnosed as having persistent asymptomatic isolated microscopic hematuria. The outcome measure for ESRD was initiation of dialysis or kidney transplantation. What did the data show?

“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 (incidence rates, 19.6 vs 0.55 per 100 000 person-years, respectively; HR, 32.4).”

Although the overall incidence of ESRD among young adults is very low, when asymptomatic microscopic hematuria is detected by positive dipstick and confirmed by microscopic analysis, clinicians should be alert to the possibility of an underlying (likely autoimmune) process that could evolve into ESRD by bearing in mind the authors’ conclusion:

“Presence of persistent asymptomatic isolated microscopic hematuria in persons aged 16 through 25 years was associated with significantly increased risk of treated ESRD for a period of 22 years, although the incidence and absolute risk remain quite low.”