Hyponatremia Common In Patients With Indwelling Peritoneal Catheters

Hyponatremia is common in patients with indwelling peritoneal catheters for drainage of malignant ascites, according to a retrospective study.

"We were surprised to find that over 80% of patients were hyponatremic after indwelling peritoneal catheter placement and that a significant proportion of patients had low sodium levels that were either unrecognized or untreated," Dr. Shruti Gupta of Brigham and Women's Hospital, Harvard Medical School, in Boston, told Reuters Health by email. "This highlights the magnitude of the problem."

Hyponatremia is common in patients with cancer and can be a challenge to manage. Drainage of malignant ascites via an indwelling peritoneal catheter (IPC) can increase sodium loss by hundreds of milliequivalents per day.

Dr. Gupta and colleagues evaluated the incidence of hyponatremia (defined as a serum sodium nadir of less than 135 mEq/L) after IPC placement and the risk factors for its development using data from their IPC registry.

Of the 309 patients included in the study, 161 (52.1%) had hyponatremia prior to IPC placement, including nine patients with severe hyponatremia (serum sodium nadir less than 120 mEq/L).

The incidence of hyponatremia after IPC placement was 84.8%, including 21 patients with severe hyponatremia, and 52 patients (16.8%) had serum sodium decreases of 10 mEq/L or more following IVC placement, the researchers report in JAMA Network Open.

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After adjustment for other factors, the odds of developing hyponatremia after IPC placement were 5.1-fold higher in patients with hepatopancreatobiliary malignancies, 7.9-fold higher in patients with lower baseline serum sodium levels, and 10% lower in patients with higher BMI.

"These findings add value to how we manage these patients - perhaps, patients who have these risk factors need closer monitoring after the IPC is placed, if within their goals of care," coauthor Dr. Maria Clarissa Tio, also of Brigham and Women's, told Reuters Health by email.

Of the 262 patients with hyponatremia after IPC placement, 61.2% were untreated for their hyponatremia or their treatment data were not recorded. Just over a quarter (28.6%) of treated patients received intravenous fluid, 3.8% had fluid restriction, 3.4% received diuretics, and 8.8% had nephrology consults.

"We want to highlight that in our experience, cancer patients who develop low sodium levels from the excessive drainage of peritoneal fluid from their IPC do get better with IV fluids," Dr. Tio said. "Knowing this, and being able to improve their sodium levels, may improve their quality of life."

Survival after IPC placement was similar in patients with severe hyponatremia (median, 35 days) and in patients with serum sodium levels above 120 mEq/L (median, 38 days).

Among the 57 patients who had urine studies done, 21 (36.8%) had hypovolemic hyponatremia. In most of the remaining cases, the cause of hyponatremia could not be determined.

"Even though IPC placement is often a palliative procedure, hyponatremia in this setting is usually responsive to the administration of fluids through an IV," Dr. Gupta said. "This could potentially improve quality of life by preventing recurrent hospitalizations for symptomatic hyponatremia."

"Our hope is to raise awareness and foster a multidisciplinary approach with oncologists and nephrologists to manage these complex patients," she said.

—Will Boggs MD

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