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Mitochondrial patients have significant problems with gut dysmotility. Dysmotility can occur at any level of the gut; the intensity of the motility problem. Viral illnesses can slow the gut further.

Disturbed colonic motility can be associated with infrequent stools (days or weeks without a stool), alternating hard stools and diarrhea, or incomplete emptying (i.e., passes some stool without complete evacuation). Some patients have difficulty passing even soft stools. On occasion stool volumes are very large ("blocking the toilet") which contributes to the difficulty in passing. Diarrhea can occur in combination with constipation or alternate with it.

Gut dysmotility likely occurs at least in part because of autonomic dysfunction (Zelnik, 1996; Chinnery, 2001) and bowel wall muscle weakness. Other symptoms of autonomic dysfunction might be present including temperature dysregulation, abnormal (usually low) basal body temperature, heat and cold intolerance, abnormal sweating patterns, tachy- and bradycardia, dizziness, orthostatic changes in heart rate and blood pressure, and bladder dysfunction (Garcia-Velasco A, 2003).

If constipation is a significant or chronic issue, it can cause poor feeding and failure to thrive. As a result, fluid intake (like calorie intake) might be suboptimal, causing or contributing to constipation.

Finally, patients with energy disorders are at risk for hypothyroidism and adrenal dysfunction each of which can cause constipation.

Mitochondrial Differential Diagnosis

1. GI causes -

a. Gut dysmotility

2. (Chronic) underhydration

3. Endocrine disease -

a. Hypothyroidism

b. Adrenal dysfunction

Assessment and Recommendations

1. Considerations:

a. Consider non-mitochondrial causes of constipation.

b. Determine what symptoms are associated with the constipation and whether or not there are any trigger factors.

2. GI causes:

a. Assess for colonic dysmotiliy. What is the child's bowel pattern - Irregular? Infrequent? Texture - hard stools and/or diarrhea, normally soft? Large volume? Lots of gas?


1. Manage for constipation.

2. If persistent or resistant to therapy, referral to a gastroenterologist may be necessary, particularly one knowledgeable in gut motility issues.

3. Hydration:

a. Assess hydration status.


1. If fluid or calorie intake is low, encourage fluids and/or calories. Remember that patients may tolerate only small amounts or volumes at one time. If a trial of IV fluids (10% dextrose with electrolytes) improves symptoms, this might be consistent with an autonomic etiology, and a plan may be necessary to guarantee the patient's calorie and/or fluid intake.

4. Endocrine causes:

a. Assess thyroid functions and adrenal status.


1. If an endocrinopathy is identified, follow-up by an endocrine specialist is appropriate.


Chinnery PF, Jones S, Sviland L, et al. Mitochondrial enteropathy: The primal pathology may not be within the gastrointestinal tract. Gut 2001;48(1):121-4.

Garcia-Velasco A, Gomez-Escalonilla C, Guerra-Vales JM, et al. Intestinal pseudo-obstruction and urinary retention: Cardinal features of a mitochondrial DNA-related disease. J Intern Med 2003;253:381-5.

Zelnik N, Axelrod FB, Leschinsky E, et al. Mitochondrial encephalomyopathies presenting with features of autonomic and visceral dysfunction. Pediatr Neurol 1996;14:251-4.

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