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Abstract: PO1152

SIADH and Postoperative Urinary Retention

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

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


  • Bakhtawar, Khawaja M., Overlook Medical Center, Summit, New Jersey, United States
  • Jalal, Abdullah, Overlook Medical Center, Summit, New Jersey, United States

Hyponatremia is a common electrolyte abnormality in hospitalized patients with increased prevalence noted in geriatric populations. The increased susceptibility is multifactorial from age-related GFR reduction in addition to medication effects (diuretics, antidepressants), decreased solute intake and endocrinopathies (SiADH). Herein we present a case of severe hyponatremia induced by urinary retention, an infrequently described and often overlooked etiology of hyponatremia in elderly patients.

Case Description

A 58-year-old male with past medical history of hypertension on amlodipine and losartan presented with nausea, emesis and abdominal pain. The patient was recently discharged 2 weeks earlier s/p uncomplicated distal pancreatectomy with splenectomy for pancreatic adenocarcinoma. Post-operative course was stable with no complications and patient was discharged home on oxycodone/acetaminophen for pain. At home, the patient noticed constipation with worsening abdominal distension with bilateral lower extremity swelling. He had been oliguric for the past week, performing manual suprapubic compression to void. On readmission patient was noted to be severely dehydrated with a large, distended abdomen. Vital signs were BP 102/53, HR 87, SpO2 97%. Notable labs include (mEq/L): Na 111, BUN 132, Cr 4.4, HCO3 18. Urine studies noted (mEq/L): Na 8, Cl <10, K 25, serum osmolality 366 mOsm/kg. Abdominal CT noted a large LUQ fluid collection, distal colonic distension with fecal retention and mild bilateral hydronephrosis. Subsequent foley insertion immediately drained 2.5L. Repeat labs 12 hours later were (mEq/L): Na 118, BUN 118, Cr 2.89. Hypotonic fluids were started to prevent Na overcorrection. Over the next several days the patient’s Serum Na (135) and renal function improved (BUN 21, Cr 0.9) back to baseline.


During the post-operative period urinary retention is commonly noted due to anesthesia, analgesics, pain and constipation. This can be exacerbated in elderly male patients due to the ubiquity of BPH. Therefore physicians must be aware of common post-operative complications of urinary retention like hyponatremia, especially given the higher prevalence and predisposition of geriatric populations to develop hyponatremia. The proposed mechanism of urinary retention induced hyponatremia involves bladder distension and/or pain-mediated ADH release.