FROM GASTROINTESTINAL ENDOSCOPY
Bowel preparation with low-volume polyethylene glycol led to hypokalemia in nearly 25% of high-risk patients who were normokalemic at baseline, according to a first-in-kind large single-center prospective study.
“Hypokalemia is frequently encountered after low-volume PEG bowel cleansing in high-risk patients,” wrote Ankie Reumkens, MD, and her associates at Maastricht University Medical Center, Maastricht, the Netherlands. The report was published online in Gastrointestinal Endoscopy. “Additional large-scale studies are needed on the prevalence of hypokalemia in nonselected populations undergoing bowel cleansing and on the occurrence of potentially very serious side effects in order to decide on screening of high-risk groups in daily clinical practice.”
Good bowel preparation is crucial to colonoscopy. Bowel preparation with both sodium phosphate and high-volume polyethylene glycol (PEG) has caused hypokalemia, but whether this is true of low-volume PEG is unclear, the investigators said. Recently, at their institution, two colonoscopy patients developed severe hypokalemia and died of ventricular arrhythmias after receiving low-volume PEG. These deaths spurred the researchers to prospectively study 1,822 colonoscopy patients who underwent bowel preparation with low-volume PEG in 2014 and who were considered at high risk of hypokalemia by their gastroenterologists or because of hospitalization or diuretic use.
The researchers measured serum potassium levels of all patients before bowel cleansing. After bowel testing, they retested a subgroup of 301 patients who were normokalemic (3.5-5 mmol/L) at baseline (Gastrointest Endosc. 2017 Feb 7. doi: 10.1016/j.gie.2017.01.040).
In all, 77 patients (4%) were hypokalemic before bowel cleansing, the researchers said. Fully one-third were hospitalized, and hospitalization remained a significant risk factor for baseline hypokalemia even after the researchers controlled for diuretic use, age, sex, and reason for colonoscopy (odds ratio, 2.5; 95% confidence interval, 1.5 to 4.2; P less than .001).
Follow-up testing showed that 71 patients (24%) who were normokalemic at baseline became hypokalemic (serum potassium less than 3.5 mmol/L) after bowel preparation with low-volume PEG. Only diuretic use remained significantly associated with this outcome after researchers accounted for age, sex, reason for colonoscopy, and hospitalization status (odds ratio, 2.3; 95% confidence interval, 1.3 to 4.0; P = .004).
This study included preselected groups of diuretic users and hospitalized patients, making it difficult to assess specific and detailed risk factors for hypokalemia, the researchers said. “Despite this limitation, our study clearly shows that hypokalemia may develop in a substantial percentage of patients after the ingestion of low-volume PEG,” they emphasized. But they recommended population-based studies to determine the true prevalence of hypokalemia after colonoscopy, examine risk factors for this outcome, and consider whether it makes sense to screen subgroups at risk.
The protocol at their hospital is to measure serum potassium before bowel cleansing in hospitalized patients and those on diuretics, they noted. Hypokalemic patients then receive oral potassium if their potassium level was 2.5-3.0 mmol/L, and intravenous potassium if their level was below 2.5 mmol/L.
The investigators reported having no funding sources and no competing interests.