Fluid accumulation syndrome (FAS) is increasingly recognised as a major determinant of adverse outcomes in critically ill patients. However, the timing and patient selection for fluid removal, also known as de–resuscitation, is a clinical conundrum and an area of ongoing research. Early de–resuscitation may induce tissue hypoperfusion and worsen organ dysfunction, whereas delayed intervention can lead to persistent fluid accumulation and its associated complications. The Furosemide Stress Test (FST), originally designed to evaluate renal functional reserve and to predict the progression of acute kidney injury and the need for renal replacement therapy, has gained traction as a potential tool for assessing a patient's readiness for de–resuscitation. By measuring the diuretic response to a protocolised FST, it may provide complementary information on renal natriuretic capacity and the potential feasibility of active de–resuscitation in appropriately selected patients. This narrative review elucidates the physiological basis of the FST, evaluates the existing evidence supporting its application in critically ill patients, and discusses its integration with haemodynamic assessments, markers of venous congestion, and other indicators of fluid tolerance. Furthermore, we propose a four–step protocol using the FST to assess readiness for de–resuscitation and to guide individualised fluid removal strategies. This represents a hypothesis–generating research framework that requires prospective clinical validation before clinical implementation.