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Background and Objectives: Glomerular hyperfiltration and albuminuria accompanied by early-stage diabetic kidney disease predict future renal failure. Cigarette smoking has reported to be associated with elevated GFR in cross-sectional studies and with renal deterioration in longitudinal studies. The degree of glomerular hyperfiltration and proteinuria associated with smoking, which presumably is a phenomenon of early renal damage, has not been investigated in a satisfying manner so far., Design, Setting, Participants, & Measurements: This study included 10,118 Japanese men aged 40 to 55 years without proteinuria or renal dysfunction at entry. Estimated GFR was calculated using the Modification of Diet in Renal Disease equation for Japanese. Glomerular hyperfiltration was defined as estimated GFR ≥117.0 ml/min per 1.73 m(2), which was the upper 2.5th percentile value of estimated GFR in the total population. Proteinuria was detected using standard dipstick., Results: During the 6-year observation period, there were 449 incident cases of glomerular hyperfiltration and 1653 cases of proteinuria. Current smokers had a 1.32-time higher risk for the development of glomerular hyperfiltration and a 1.51-time higher risk for proteinuria than nonsmokers after adjustment for baseline age, body mass index, systolic and diastolic BP, antihypertensive medication, diabetes, alcohol consumption, regular leisure-time physical activity, and estimated GFR. Both daily and cumulative cigarette consumption were associated with an increased risk for glomerular hyperfiltration and proteinuria in a dose-response manner., Conclusions: In middle-aged Japanese men, smoking was associated with an increased risk of glomerular hyperfiltration and dipstick proteinuria. Of importance, past smokers did not exhibit any increased risk for these conditions.

Background/aims: No prospective studies have estimated the association between white blood cell (WBC) count and the risk of proteinuria. We prospectively examined the relationships of WBC count, as a marker of inflammation, with two outcomes: proteinuria and low estimated glomerular filtration rate (eGFR)., Methods: We enrolled 10,008 Japanese men aged 40-55 years who had neither proteinuria nor low eGFR and were not taking antihypertensive medications at entry. Proteinuria was defined as 1+ or higher on urine dipstick. Low eGFR was defined if eGFR was <60 ml/min/1.73 m(2)., Results: During the 49,644 person-years of follow-up, 1,557 cases of proteinuria were confirmed. After adjusting for age, body mass index, fasting plasma glucose, systolic blood pressure, diastolic blood pressure, antidiabetic medications, alcohol consumption, smoking, regular leisure-time physical activity and eGFR, the highest quintile (≥7.51 × 10(3)/μl) of WBC count was independently associated with an increased risk of incidence of proteinuria [HR: 1.45 (95% CI: 1.23-1.73)] compared with the lowest quintile (≤4.80 × 10(3)/μl). On the other hand, during 52,833 person-years, we confirmed 439 cases of low eGFR. In multivariate models, there was no association between WBC count and low eGFR., Conclusion: Elevated WBC count was independently associated with an increased risk of proteinuria, but not low eGFR., (Copyright © 2011 S. Karger AG, Basel.)