Proteinuria plays a central role in the diagnosis of kidney disease and has a high prognostic value. The test methods used differ considerably regarding impact on test accuracy, sensitivity, and specificity. Therefore, knowledge of the methodology is crucial for the interpretation of the results. In addition to the distinction between semi-quantitative and quantitative tests, there are also relevant differences within the two methods. In general, semi-quantitative tests are easy to handle but have limitations such as: i) incomplete quantification, ii) a lack of specificity regarding the type of proteinuria, iii) a high rate of false positive tests with the need for re-testing with a quantitative method for verification.