Screening for Albuminuria Identifies Individuals at Increased Renal Risk

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Abstract
It is unknown whether screening for albuminuria in the general population identifies individuals at increased risk for renal replacement therapy (RRT) or accelerated loss of renal function. Here, in a general population-based cohort of 40,854 individuals aged 28 to 75 yr, we collected a first morning void for measurement of urinary albumin. In a subset of 6879 individuals, we measured 24-h urinary albumin excretion and estimated GFR at baseline and during 6 yr of follow-up. Linkage with the national RRT registry identified 45 individuals who started RRT during 9 yr of follow-up. The quantity of albuminuria was associated with increased renal risk: the higher the level of albuminuria, the higher the risk of need for renal replacement therapy and the more rapid renal function decline. A urinary albumin concentration of ≥20 mg/L identified individuals who started RRT during follow-up with 58% sensitivity and 92% specificity. Of the identified individuals, 39% were previously unknown to have impaired renal function, and 50% were not being medically treated. Restricting screening to high-risk groups (e.g., known hypertension, diabetes, cardiovascular disease [CVD], older age) reduced the sensitivity of the test only marginally but failed to identify 45% of individuals with micro- and macroalbuminuria. In conclusion, individuals with elevated levels of urinary albumin are at increased risk for RRT and accelerated loss of renal function. Screening for albuminuria identifies patients at increased risk for progressive renal disease, 40 to 50% of whom were previously undiagnosed or untreated.