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


  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.
  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.
  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.
  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.


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?

200 pearls and counting! Take the Pearls4Peers quiz #2!

Multiple choice (choose 1 answer)
1. Which of the following classes of antibiotics is associated with peripheral neuropathy?
a. Penicillins
b. Cephalosporins
c. Macrolides
d. Quinolones



2. The best time to test for inherited thrombophilia in a patient with acute deep venous thrombosis is…
a. At least 1 week after stopping anticoagulants and a minimum of 3 months of anticoagulation
b. Just before initiating anticoagulants
c. Once anticoagulation takes full effect
d. Any time, if suspected



3. All the following is true regarding brain MRI abnormalities following a seizure, except…
a. They are observed following status epilepticus only
b. They are often unilateral
c. They may occasionally be associated with leptomeningeal contrast enhancement
d. Abnormalities may persist for weeks or months



4. Which of the following is included in the quick SOFA criteria for sepsis?
a. Heart rate
b. Serum lactate
c. Temperature
d. Confusion



5. All of the following regarding iron replacement and infection is true, except…
a. Many common pathogens such as E.coli and Staphylococcus sp. depend on iron for their growth
b. Association of IV iron replacement and increased risk of infection has not been consistently demonstrated
c. A single randomized-controlled trial of IV iron in patients with active infection failed to show increased infectious complications or mortality with replacement
d. All of the above is true


True or false

1. Constipation may precede typical manifestations of Parkinson’s disease by 10 years or more
2. Urine Legionella antigen testing is >90% sensitive in legionnaire’s disease
3. Spontaneous coronary artery dissection should be particularly suspected in males over 50 years of age presenting with acute chest pain
4. Urine dipstick for detection of blood is >90% sensitive in identifying patients with rhabdomyolysis and CK >10,000 U/L
5. Diabetes is an independent risk factor for venous thrombophlebitis




Answer key
Multiple choice questions:1=d; 2=a;3=a;4=d;5=c
True or false questions:1=True; 2,3,4,5=False


200 pearls and counting! Take the Pearls4Peers quiz #2!

Can constipation precede the diagnosis of Parkinson’s disease by years?

Yes! Although the association of constipation and Parkinson’s disease (PD) is well known, less appreciated is that constipation may be among the earliest symptoms of PD, affecting 50% of patients for up to 20 years before the onset of motor symptoms.1  

A 2016 systematic review and meta-analysis found that patients with constipation were at significantly higher risk of developing subsequent PD (O.R. 2.27, 95% CI 2.1-2.46).2 Even, when analysis was restricted to studies assessing constipation more than 10 years prior to PD, the risk was equally elevated. In an interesting longitudinal study in which information on the frequency of bowel movements was collected from men aged 51-75 y, a strong association between < 1 bowel movement daily and subsequent diagnosis of PD was reported (average followup 12 y).3

Given the potential multicentric nature of neurodegenerative process in PD, these findings are perhaps not too surprising. Inflammation and other pathological processes in PD may involve not only the brain but also the intestine, leading to uncoordinated bowel-related muscle involvement and transit disorder, respectively.1 Indeed, Lewy bodies and α-synucleine immunoreactive inclusion bodies have been observed in the intramural ganglia of the GI tract of PD patients.4

Bonus Pearl: Did you know that caffeine may reduce the risk of PD?5

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  1. Chen Y, Yu M, Liu X, et al. Clinical characteristics and peripheral T cell subsets in Parkinson’s disease patients with constipation. Int J Clin Exp Pathol 2015;8:2495-2504.
  2. Adams-Carr KL, Bestwick JP, Shribman S, et al. Constipation preceding Parkinson’s disease: a systematic review and meta-analysis. J Neurol Neurosurg Psychiatry 2016;87:710-6.
  3. Abbott RD, Petrovitch H, White LR, et al. Frequency of bowel movements and the future risk of Parkinson’s disease. Neurology 2001;14:57:456-62.
  4. Jost WH. Gastrointestinal dysfunction in Parkinson’s disease. J Neurol Sci 2010;289;69-73.
  5. Costa J, Lunet N, Santos C, et al. Caffeine exposure and the risk of Parkinson’s disease: a systematic review and meta-analysis of observational studies. J Alzheimers Dis 2010;20 (Suppl 1):S221-38.


Can constipation precede the diagnosis of Parkinson’s disease by years?

How might constipation lead to urinary retention?

The association between constipation and urinary retention is well known (1,2).

Several mechanisms may explain this relationship,  including sharing of the innervations of the internal anal and urinary sphincters  via S2-S4 nerve roots, and the presence of impacted stool in the rectum leading to invaginations in the posterior wall of the bladder and urethral obstruction (1,2). 

Interestingly, in laboratory experiments involving rats, rectal distention with a balloon diminished bladder contractility (3).   So, along with many other factors, constipation should routinely be considered a potential cause of acute urinary retention.  

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1. Selius BA, Subedi R. Urinary retention in adults: diagnosis and initial management. Am Fam Physician 2008;77:643-650.  

2. Ariza Traslavina, Del Ciampo LA, Ferraz IS. Acute urinary retention in a pre-school girl with constipation. Rev Paul Pediatr 2015;33:488-492.

3. Miyazato M, Sugaya K, Nishijima S, et al. Rectal distention inhibits the spinal micturition reflex via glycinergic or GABAergic mechanisms in rats with spinal cord injury. Urol Int  2005;74:160-65.

How might constipation lead to urinary retention?