Has the Time Come to Include Urine Dipstick Testing in Screening Asymptomatic Young Adults?
Authors: Robert S. Brown
Journal: JAMA (2011)

URINALYSIS WAS ONCE A STANDARD SCREENING TEST in routine health evaluation but more recently has not been advised for healthy individuals or unless patients are 60 years or older or at high risk for kidney or cardiovascular disease. Although blood tests have replaced urine tests for detecting diabetes, the urine dipstick test remains a simple means of detecting unsuspected hematuria, proteinuria, or both. Are those findings common enough, and more importantly, serious enough to warrant recommending urine dipstick testing as a simple, low-cost screening tool for asymptomatic adolescents and all adults? “Isolated”microscopichematuria,definedashematurianot visibletothenakedeyeandunaccompaniedbyproteinuria,may be detected incidentally in asymptomatic individuals by a urinarydipsticktest forhemeandconfirmedbymicroscopyof the urinarysediment.Microscopichematuriamaybetransientand has been found to have a widely variable prevalence ranging from0.18%to16.1%. Evenwhenmicroscopichematuriapersistsonsubsequenturinalyses, furtherevaluationoften fails to find a cause; in these cases, the condition generally has been considered “benign hematuria” or, if familial, “benign familialhematuria.”Renalbiopsiesareusuallynotconsideredhelpful in patients with isolated microscopic hematuria, and even when biopsies have been performed, hematuria is often unexplainedbyanyabnormality,orhistopathologymayshowvarious glomerulopathies. Although the short-term prognosis of unselected patients with isolated microscopic hematuria has been favorable, long-term prognosis has been unknown. In this issue of JAMA, Vivante and colleagues report their findings from a longitudinal study of 1.2 million male and female adolescents and young adults, aged 16 to 25 years, who underwent urinary screening examinations and 21 years of follow-upforthedevelopmentofend-stagerenaldisease(ESRD) treated by dialysis or kidney transplantation. In this large unselected cohort limited to Israeli Jews examined for required military service, 0.3% were initially found to have persistent asymptomatic isolatedmicroscopichematuriawithanegative evaluation (as defined in Figure 1 in the article), a normal serumcreatininelevel,andtheabsenceofproteinuriagreaterthan 200mgperday.During theensuing21years, treatedESRDdevelopedin0.70%of individualswith,and0.045%ofthosewithout,microscopichematuriainitially.TheincreasedriskofESRD associatedwithmicroscopichematuriayieldedanadjustedhazard ratio (HR) of 18.5 (95% confidence interval, 12.4-27.6). Amongpersonswithmicroscopichematuria,ESRDtreatment was started at an earlier mean age (34 vs 38 years) and was attributed mainly to glomerulopathies. The study documents that the prevalence of persistent microscopichematuria inanasymptomaticyoungpopulationwas low and twice as frequent in male (0.4%) than female (0.2%) individuals, a point of uncertainty previously. Furthermore, hematuriawasassociatedwitha lowbutsignificantly increased riskforESRD,accountingforanestimated4.3%oftreatedESRD in the Israeli Registry. The size of this study and completeness of follow-up are unique, although the inclusion of only Israeli Jewsmay limit applicabilityof the findings tootherpopulation groups, many of which have even higher rates of ESRD. It is also uncertain how many patients with microscopic hematuriamighthavehadmildproteinuria thatmightnowbedetected as microalbuminuria. What should thecliniciandowhenmicroscopicheme isdetected by a positive dipstick test result? First, confirm the hematuria by finding 2 to 5 or more red blood cells (RBCs) per high-power field by microscopic analysis of the urinary sediment on at least 2 occasions unrelated to recent menstruation, exercise, trauma, or sexual activity. The finding of acanthocytic RBCs or RBC casts would suggest a glomerular source, as may concomitant proteinuria or an elevated serum creatinine level. In patients without an apparent glomerular etiology,aurologicevaluationisadvised,includingradiologicimaging of theurinary tract,preferablybycomputed tomographyscan, forallpatientsaswellascystoscopyandurinecytologyforthose withriskfactors forbladdercanceror thoseolder than40years or 50 years. Prior to the study by Vivante et al, patients with isolatedmicroscopichematuriaandanegativeevaluationwere usually considered to have benign hematuria and required no follow-up.Nowit seemsreasonable toreevaluatesuchpatients every1 to2years for apossible increased incidenceofproteinuria, hypertension, or renal insufficiency. In the United States, because the prevalence of chronic kidneydisease(CKD)isestimatedtobefrom70-to200-foldgreater than the prevalence of treated ESRD, perhaps an argument could be made for the inclusion of dipstick testing for hema-