Could constipation contribute to hyperkalemia in my patient with chronic kidney disease?

Yes! Constipation may be an important contributor to hyperkalemia in some patients with chronic kidney disease (CKD).

 Under normal conditions, 80-90% of excess dietary potassium (K+) is excreted by the kidneys, with the remainder excreted through the GI tract.1 However, in advanced CKD, particularly in the setting of end-stage kidney disease (ESKD), the GI tract assumes a much more important role in maintaining K+ balance. 

As early as 1960’s, the daily fecal excretion of K+ was found to be directly related to the wet stool weight, irrespective of creatinine clearance. Furthermore, K+ excretion in stool was as high as ~80% of dietary intake (average 37%) in some hemodialysis (HD) patients compared to normal controls (average 12%). 2

Such increase in K+ excretion in the GI tract of patients with CKD was later found to be primarily the result of K+ secretion into the colon/rectum rather than reduced dietary K+ absorption in the small intestine 1,3, was inversely related to residual kidney function, and as a consequence could serve as the main route of K+ excretion in patients with ESKD. 4

Collectively, these findings suggest that in addition to non-dietary factors such as medications, we may need to routinely consider constipation as a potential cause of hyperkalemia in patients with advanced CKD or ESKD. 1

Bonus Pearl: Did you know that secretion of K+ by the apical surface of colonic epithelial is mediated in part by aldosterone-dependent mechanisms? 5

References

  1. St-Jules DE, Goldfarb DS, Sevick MA. Nutrient non-equivalence: does restricting high-potassium plant foods help to prevent hyperkalemia in hemodialysis patients? J Ren. Nutr 2016;26: 282-87. https://www.ncbi.nlm.nih.gov/pubmed/26975777
  2. Hayes CP, McLeod ME, Robinson RR. An extrarenal mechanism for the maintenance of potassium balance in severe chronic renal failure. Trans Assoc Am Physicians 1967;80:207-16.
  3. Martin RS, Panese S, Virginillo M, et al. Increased secretion of potassium in the rectum of humans with chronic renal failure. Am J Kidney Dis 1986;8:105-10. https://www.ncbi.nlm.nih.gov/pubmed/3740056
  4. Cupisti A, Kovesdy CP, D’Alessandro C, et al. Dietary approach to recurrent or chronic hyperkalemia in patients with decreased kidney function. Nutrients 2018, 10, 261;doi:10.3390/nu10030261. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872679/
  5. Battle D, Boobes K, Manjee KG. The colon as the potassium target: entering the colonic age of hyperkalemia treatment. EBioMedicine 2015;2: 1562-1563. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740340/pdf/main.pdf

 

Contributed in part by Alex Blair, MD, Mass General Hospital, Boston, MA.

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Could constipation contribute to hyperkalemia in my patient with chronic kidney disease?

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