INTRODUCTION: Clinical laboratories play an important role in the diagnosis and monitoring of chronic kidney disease (CKD). Our aim was to evaluate the performance of qualitative and semi-quantitative albumin-to-creatinine ratio (ACR) and protein-to-creatinine ratio (PCR) test strip results as screening tools for albuminuria in multiple representative patient cohorts. MATERIALS AND METHODS: ACR and PCR were evaluated in both cross-sectional (n = 940) and validation (n = 927) patient cohorts. Semi-quantitative urinary ACR and PCR were performed using a UC-3500 instrument (Sysmex, Kobe, Japan). The diagnostic performance of semi-quantitative ACR and PCR was determined using quantitative ACR and PCR as reference method. RESULTS: In the cross-sectional cohort, a sensitivity and specificity of 78.1% and 93.3%, respectively, were obtained for semi-quantitative ACR at a cut-off of 30 mg/g creatinine, with an overall agreement of >
90% between both methods. The sensitivity and specificity increased in the target population (validation cohort) to 89.9% and 92.1%, respectively. In contrast, the sensitivities of qualitative protein concentration (78.6%) and semi-quantitative PCR (69.8%) were lower. CONCLUSION: The results confirm that urine test strip readouts are a valuable screening tool for CKD in low-risk individuals. ACR should be the preferred criterion for reflex testing when using a urine test strip for screening CKD.