A general concept for the development of flow analysis system for non-invasive, bloodless monitoring of uremic toxins' removal in the course of clinical hemodialysis treatment is presented. The monitor operates in both (discrete and continuous) modes of measurements. In this study as a model uremic marker creatinine has been chosen. The monitor is based on solenoid operated microdevices (pumps and valves) and an optoelectronic flow-through detector made of paired light emitting diodes allowing photometric determination of this metabolite using Jaffé method. Additionally, a simple two microsolenoid pump-based module allowing the modeling of toxin removal by artificial kidney has been developed. The developed monitor has been validated with real samples of postdialysate fluid produced by artificial kidney in the course of clinical hemodialysis treatment. The results of hemodialysis monitoring are fully comparable with those obtained using reference off-line method.