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Abstract: TH-PO180

A Case of Hyperosmolar Hyponatremia from Polyethylene Glycol (PEG)

Session Information

Category: Trainee Case Report

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Nutt, Max, Wake Forest Baptist Health Internal Medicine, Winston Salem, North Carolina, United States
  • DuBose, Thomas D., Wake Forest Baptist Health Internal Medicine, Winston Salem, North Carolina, United States
  • Pirkle, James L., Wake Forest Baptist Health, Winston Salem, North Carolina, United States
  • Tucker, Bryan, Wake Forest Baptist Health, Winston Salem, North Carolina, United States

Group or Team Name

  • Wake Forest Baptist Health - Nephrology
Introduction

N/A

Case Description

69 year old man with pulmonary sarcoidosis presented to the ER with shortness of breath, diagnosed with acute pneumonia and treated with antibiotics, with gradual improvement in dyspnea. Hospital course was complicated by an ileus, for which increasing amounts of polyethylene glycol (PEG) was prescribed. On hospital day 10 the laboratory data revealed acute worsening of hyponatremia (123mmol/l), hyperkalemia (5.5mmol/l), and a mild non-oliguric AKI, prompting nephrology consultation.

Discussion

The measured serum osmolality of our patient was normal (277 mOsm/kg), and a low whole blood sodium (127mmol/L) ruled out pseudohyponatremia. The serum osmolar gap was elevated at nearly 20 mOsm/kg, indicating the presence of an unmeasured osmolyte. A negative correlation between the patient’s serum sodium and potassium was observed, such that when [Na+] decreased, [K+] increased (Image 1).

Searching the chart for known etiological agents that may act as an effective osmole and produce these series of events was unsuccessful. Our attention was focused on PEG, which was being administered in high doses (170 grams cumulatively) in the absence of a bowel movement. A dose-dependent temporal relationship between PEG administration and hyponatremia was observed, supporting the diagnosis of PEG-induced hyponatremia. A proposed mechanism is outlined and illustrated in Image 2.

When PEG was discontinued by Nephrology, the electrolyte abnormalities corrected rapidly.

Figure 1. Lab Data relevant to PEG dosing