Diuretic Use Increases Colonoscopy Patients’ Risk of Hypokalemia

By Scott Baltic

March 09, 2017

NEW YORK (Reuters Health) - Hypokalemia is not uncommon after low-volume PEG (polyethylene glycol) bowel cleansing, particularly in patients who use diuretics, a new report confirms.

As reported online February 7 in Gastrointestinal Endoscopy, the impetus for the study arose from two recent cases the authors encountered in which severe postcolonoscopy hypokalemia had fatal consequences.

Each patient had received bowel preparation with low-volume PEG, and each developed ventricular arrhythmia a few hours following colonoscopy, for which resuscitation was unsuccessful. Laboratory findings showed severe hypokalemia.

Because colorectal cancer (CRC) screening programs are implemented worldwide and the number of colonoscopies has been rising, the authors wrote, “more patients will be exposed to colonoscopy and bowel cleansing-related risks, including hypokalemia. While waiting for more evidence, endoscopists should be aware of the prevalence of hypokalemia after bowel cleansing and potential risks.”

Led by Dr. Ankie Reumkens, the research team studied all patients who underwent colonoscopy during 2014 at Maastricht University Medical Center in the Netherlands and were considered to be at risk for hypokalemia either because they were diuretic users, hospitalized, or deemed to be at risk by a gastroenterologist for reasons such as chronic diarrhea or inflammatory bowel disease. The median age was 68.

Serum potassium levels were measured before bowel preparation and, in a random 20% of patients with normal serum potassium levels, after bowel cleansing as well. Patients diagnosed with hypokalemia before bowel prep received potassium supplementation.

All patients received at least 2L of low-volume PEG with ascorbic acid for bowel preparation.

Among the 1,822 patients whose serum potassium levels were measured before colonoscopy, 77 (4.2%) had hypokalemia before bowel preparation. Hospitalized patients were more likely than non-hospitalized patients to have hypokalemia at this point.

Of the 1,633 patients with normal or high potassium levels (112 had hyperkalemia), a random 301 were tested on the day of colonoscopy, after bowel cleansing. Of these, 71 (23.6%) had developed some degree of hypokalemia, which was severe in two, moderate in 11, and mild in 58.

Hypokalemia was significantly more frequent in patients who had used diuretics (p=0.004), most commonly single thiazide diuretics.

This study is mostly “documenting a lot we already know . . . High-risk patients are at high risk,” Dr. John H. Marks, chief of colorectal surgery at Lankenau Medical Center, Wynnewood, Pennsylvania, told Reuters Health in a phone interview.

Nevertheless, said Dr. Tonia Young-Fadok, of the Mayo Clinic, Phoenix, and a board member of the Society of American Gastrointestinal and Endoscopic Surgeons in a phone interview, the study is a useful reminder that “colonoscopy should not be just a checkbox” and needs be carefully considered in all its aspects, including bowel preparation.

Dr. Reumkens did not reply to a request for comment.

SOURCE: https://bit.ly/2nfwfv4

Gastrointest Endosc 2017.