Elevated white blood cell count worsens proteinuria but not estimated glomerular filtration rate: the Kansai Healthcare Study.

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.