Constipation is a common secondary symptom in a wide variety of diseases, including chronic kidney disease (CKD). While constipation is not a life-threatening complication of CKD, except in rare cases, several studies have shown that it is linked with increased mortality, even in the general population. A nationwide study in the U.S. reported that constipation was associated with a higher incidence of CKD and kidney failure.* 

What factors can cause constipation in people with CKD?

Many factors influence the development of constipation in CKD patients, including:

• Dialysis modality
• Gut dysbiosis
• Lifestyle
• Comorbidities (related medical conditions)
• Medications
• Diet

Dialysis modality

The incidence of constipation after the induction of dialysis therapy is gaining in importance. A recent study revealed that the colonic transit time (or time it takes for feces to move through the eliminatory tract) of patients treated with hemodialysis (HD) or peritoneal dialysis (PD) was significantly longer than that of healthy subjects. 

The method of dialysis used is also significant. Previous studies have consistently found that constipation prevalence was lower in PD patients than HD patients. Lifestyle factors and medication usage common to PD may help explain this. It is unknown whether constipation increases in proportion with CKD progression.

Gut dysbiosis

CKD is also associated with gut dysbiosis, which refers to changes in your gut microbiota (bacteria, viruses, protozoa, fungi, etc.) that cause an imbalance of these microorganisms in the body. Gut dysbiosis has begun to attract some attention in CKD research, due to the widely recognized gut-kidney axis. 

In CKD patients, gut dysbiosis causes uremic toxins to build up in the body, resulting in oxidative stress and chronic inflammation—both of which facilitate the progression of CKD and induce constipation. Gut dysbiosis has even been observed in patients with mild, early-stage CKD and associated with several other health conditions, including obesity, atherosclerosis, and cancer.  

Lifestyle

Various population surveys link lifestyle habits and constipation in people living with CKD, specifically:

• Physical activity is lower in dialysis patients than in healthy subjects. 
• Lower activity is common even between dialysis treatments.
• Over seventy-eight percent (78.5%) of HD patients suppressed the urge to defecate during sessions. 
• Many HD patients use laxatives every other day, to avoid defecation during HD sessions.

Related medical conditions

Several related medical conditions, or comorbidities, that have been found in many CKD patients may also contribute to secondary constipation, such as:

• Endocrine/metabolic diseases, like diabetes, hypercalcemia (too much calcium in the blood), hypothyroidism, and hyperparathyroidism
• Cerebrovascular disease
• Neurological diseases, like autonomic neuropathy and stroke
• Amyloidosis and scleroderma
• Depression and anxiety

Other medical conditions that can cause constipation include:

• Parkinson’s disease
• Spinal cord injury 
• Inflammatory bowel disease (IBD), like ulcerative colitis and Crohn’s disease
• Structural abnormalities

Medications

A significant number of medications are known to cause constipation, including:

• Serotonin receptor blockers
• Opioids
• Anticholinergic agents
• Anticonvulsants, 
• Antihypertensive agents
• Antidepressants
• Chemotherapy agents
• Potassium-binding resins
• Phosphate binders

Since people with CKD generally take many kinds of medications, determining which ones are responsible for constipation can be challenging. 

Diet

CKD-friendly diets are known for their restriction of fiber-rich fruit and vegetable consumption, along with reduced fluid intake—particularly when the disease is in advanced stages. Both of these factors have been associated with the development of constipation, though more research is needed concerning the implications of fiber restriction and fiber therapy for patients with CKD. 

How to treat constipation if you have CKD

Since the development of constipation in CKD has many factors, a variety of treatment approaches should be considered, including:

• Reducing or eliminating certain medications that cause constipation
• Adding natural agents, such as probiotics, prebiotics, or synbiotics
• Laxatives to soften stool and facilitate bowel movements (to be used only when prescribed)
• Serotonin type 4 receptor agonist drugs to improve peristalsis
• Lifestyle adjustments, such as increased exercise and modifying your defecation posture for better angle, pressure, and release

Further research is necessary to better understand the many causes of constipation in people living with CKD and to determine the best ways to treat and manage it.  

*Ikee, R., Yaho, K., and Tsuru, T. (2019, Dec. 12). Constipation in Chronic Kidney Disease: It Is Time to Reconsider. Renal Replacement Therapy. https://rrtjournal.biomedcentral.com/articles/10.1186/s41100-019-0246-3