Kidney Week

Abstract: FR-PO0629

A Case of Severe Postobstructive Diuresis Requiring Prolonged Inpatient Treatment

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 2
  November 07, 2025 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

• Abilmona, Dayana, MedStar Franklin Square Medical Center, Baltimore, Maryland, United States

Dayana Abilmona, MD

• Amar Jeet Singh, Ishvinder Jeet Singh, MedStar Franklin Square Medical Center, Baltimore, Maryland, United States

Ishvinder Jeet Singh Amar Jeet Singh, MBChB

• Karam, Sabine, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States

Sabine Karam, MD

• Al-Talib, Khalid K., MedStar Franklin Square Medical Center, Baltimore, Maryland, United States

Khalid K. Al-Talib, MD, FASN

Introduction

Post obstructive diuresis (POD) is defined as urine output (U/O) exceeding 200 mL/hr for at least 2 hours. POD generally resolves in 2-5 days. We present a case of severe POD requiring treatment with vasopressin and vasotonics for 4 weeks after the relief of obstruction.

Case Description

A 57-year-old man with hypertension and remote history of drug use presented with a several days history of progressive right flank pain and an elevated creatinine (Cr) at 12.2 mg/dL from a baseline of 0.9 mg/dL 2 years back. CT scan demonstrated severe bilateral hydronephrosis without obstructing calculi. Following Foley catheter insertion, the patient was polyuric with 4-7 L of output daily. He had severe symptomatic orthostatic hypotension despite oral and IV fluids administration and was subsequently initiated on fludrocortisone. The urine osmolarity (UOsm) fluctuated between 218 and 259 mosm/kg while serum sodium was 139-140 mEq/L. Cr stabilized at 4.5 mg/dL. As he remained severely polyuric, he was started on desmopressin, followed by midodrine. The Uosm improved to 397 mOsm/kg and maintenance fluids were decreased. During the 4^th week, fludrocortisone and midodrine were discontinued upon improvement of the polyuria and resolution of the orthostasis. The patient was discharged home after which desmopressin was tapered down until cessation.

Discussion

POD is generally a self-limiting entity managed with supportive treatment. Physiologically, POD results in excretion of retained solutes and water secondary to obstruction resulting in osmotic diuresis. POD may also entail pathological free water diuresis in the absence of expanded intravascular volume or excess solute. This results from partial nephrogenic diabetes insipidus due to loss of juxtaglomerular nephrons, decreased medullary gradient, downregulation of aquaporins and failure of the collecting duct to respond to ADH. Our patient’s orthostatism and polyuria were initially addressed with fluids and fludrocortisone. On follow up, a component of free water diuresis was evident, and desmopressin was added with significant decrease in urine output and simultaneous increase in urine osmolarity. This unusual and severe course may be predicted by the chronicity of the obstruction and resulting severity of the kidney insult.

Digital Object Identifier (DOI)

• doi: 10.1681/ASN.2025h5ymybqd