As The River Flows: A Case Report of Post Obstructive Diuresis

Post obstructive diuresis (PObD) is a medical complication that occurs after a period of urinary obstruction. It is defined as a prolonged production of urine of at least 200 cc/hour for two consecutive hours or over 3 L of urine production over a 24-hour period following relief of urinary retention or an obstructive uropathy. Physiologic PObD lasts for 24 h while pathologic PObD lasts for over more than a 48-hour period and can lead to massive electrolyte deficiencies as well as the possibility of hypotension and consequent shock. The typical pathophysiology of pathologic PObD involves medullary washout from urinary retention and tubular injury, downregulation of sodium transport receptors in the thick ascending loop of Henle, a reduction in the glomerular filtration rate (GFR), and a poor response to antidiuretic hormone (ADH). Guidelines on the treatment of PObD rely on the regulation of fluid maintenance, however, they do not definitively describe how to manage contributive factors to the pathology. We discuss the case of a patient who developed severe PObD with a tailored approach to treating the underlying pathophysiologic mechanisms contributing to pathologic PObD while utilizing markers to guide patient management.

A 79-year-old male with a past medical history of severe aortic stenosis, coronary artery disease, hyperlipidemia and mild Alzheimer's disease presented with invasive bladder cancer and consequent obstructive uropathy. An ileal conduit was created. Massive urinary diuresis occurred for more than 48 h once the obstruction was relieved and subsequently, our patient went into shock. Nephrology was consulted and a treatment plan was initiated that targeted appropriate fluid administration to overcome the massive diuresis while also focusing on improving the medullary gradient and response to anti-diuretic hormone. Our patient's condition improved after our multifaceted therapeutic approach.

This case report highlights the importance of maintaining appropriate fluid administration to treat fluid loss while avoiding augmentation of the diuresis. We also demonstrate the significance of a treatment plan that targets the pathophysiological mechanisms contributing to PObD to help treat our patient's condition.