A 75 year old male with a history of hypertension and diabetes arrived with a week history of diarrhea, reporting 10-15 episodes per day, and a two to three day history of increased urinary frequency and dysuria. His family reported that there were multiple episodes of fecal incontinence over the past three days with increasing polyuria and dysuria. He denied recent antibiotic use, fever, chills, or recent travel within the past year. His medications were furosemide, metformin, and lopressor.
In the ED, he was afebrile and hemodynamically stable. He was found to have an initial serum sodium (Na) of 115mg/dl, serum uric acid 2.4mg/dL and serum osmolality (osm) was 244mosm/kg and a leukocytosis to 28.1K/uL with neutrophil count of 88 percent. Urine electrolytes showed urine Na 62mg/dL and osm 304mosm/kg. We attributed his hyponatremia to his history of “diarrhea,” though the workup was more suggestive of SIADH, euvolemia, a low serum uric acid and a formed stool sample. He was given 2 liters normal saline followed by normal saline infusion at 125cc per hour and empirically started on antibiotics for infectious “diarrhea.” Repeat labs at 4 hours showed, his Na increased to 119, but fell to 116 at 16 hours with resolution of his leukocytosis. He developed lower extremity edema and furosemide was added with his repeat Na of 118. Serial exams and reports from nurses revealed he had formed stools, with overflow incontinence and a distended urinary bladder with normal creatinine. A foley was inserted with 1200cc urine output within 5 minutes. Six hours after the foley insertion, his Na levels increased to 129 and normalized within 24 hours of insertion.
Discussion: SIADH is a common etiology of hyponatremia in elderly patients. Several disease entities have been associated with SIADH, such as malignancy, pulmonary diseases, intracranial pathology, severe pain, nausea and vomiting, and some medications. Our patient presented with a symptom of “diarrhea” which turned out to be overflow incontinence due to retention. His work up for hyponatremia met the criteria of SIADH: euvolemic status, a normal urine Na, a normal urine osm and a low serum uric acid. He failed to respond to isotonic fluids with loop diuretics. Foley catheter insertion corrected serum Na level within six hours. There are case reports of SIADH associated with urinary retention in elderly patients, however most could not exclude other contributing etiologies. The proposed mechanism is bladder distention or pain stimulates the inappropriate release of ADH in the hypothalamus, causing the hyponatremia. Isotonic or hypertonic IVF hydration and loop diuretics could only exacerbate the distention of the bladder which explains why our patient did not respond to our treatments until the foley was placed.
Conclusions: Our case supports the notion that urinary retention could cause hyponatremia via a mechanism of SIADH and should be considered when evaluating an elderly hyponatremic patient refractory to initial therapies.
To cite this abstract:Gong J, Yang D. Siadh Caused by Urinary Retention in an Elderly Patient. Abstract published at Hospital Medicine 2016, March 6-9, San Diego, Calif. Abstract 520. Journal of Hospital Medicine. 2016; 11 (suppl 1). https://www.shmabstracts.com/abstract/siadh-caused-by-urinary-retention-in-an-elderly-patient/. Accessed April 9, 2020.