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Anorexia and Poor Feeding

A subset of patients with mitochondrial disease have significant and/or recurrent problems with eating. Since adequate nutritional support is essential to optimizing well-being in mitochondrial disease, an inadequate diet (nutrients and/or calories) can impact health; symptoms of the disease (such as fatigue or headaches or dizziness) may worsen.

Neurologic and gastrointestinal involvement in mitochondrial disease is intense, diffuse and overlapping. Those individuals with visceral involvement had a high likelihood of having or developing multiple organ involvement (Debray, 2007).

Obstacles to adequate intake can be mechanical in nature due to a problem with gut motility; this can include gastroesophageal reflux, slow gastric emptying with bloating and pain, intestinal dysmotility with the same symptoms, or even frank pseudo-obstruction. When constipation is severe or chronic, intake can drop as patients feel full or have problems with pain or gas. Gut dysmotility likely occurs at least in part because of autonomic dysfunction (Zelnik, 1996) and/or bowel smooth 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.

An uncoordinated suck or swallowing reflex may be due to neurologic impairment (e.g., bulbar weakness) and could become worse when the patient is sick or tired.

Problems in other organs can also impact intake. Mitochondrial liver disease or pancreatitis or renal disease can be associated with anorexia. Chronic or severe headaches or migraine are often associated with nausea or vomiting. When respiratory muscle weakness occurs and is associated with tachypnea, the patient's calorie intake may drop (while calorie needs increase).

Finally, psychological issues related to developmental delays or having a chronic illness can impact on appetite.

Mitochondrial differential diagnosis

  1. GI causes:
    1. Gastroesophageal reflux
    2. Gastroparesis
    3. Intestinal dysmotility
    4. Constipation
    5. Liver disease
    6. Pancreatitis
  2. Neurologic causes:
    1. Headache or migraine
    2. Uncoordinated suck and/or swallow
  3. Autonomic dysfunction
  4. Respiratory distress
    1. Respiratory muscle weakness and tachypnea
    2. Aspiration
  5. Psychological causes

Assessment and Recommendations:

  1. GI causes:
    1. Assess the patient's nutrition, specifically calorie intake;
    2. Assess for GI issues related to poor intake;
    3. Assess for signs of liver disease;
    4. Assess for evidence of pancreatitis.


1. Assess the patient's calorie intake;

2. If appropriate, consider blood testing to assess for liver or kidney disease, or pancreatitis;

3. Referral to a gastroenterologist, particularly one knowledgeable in gut motility issues.

  1. Neurologic causes:
    1. Assess for headaches and migraine. Are there associated symptoms such as an aura, increased sensitivity to light or sound, or nausea or vomiting? Is there a family history of migraine?
    2. If the patient is choking or having difficulty with chewing or swallowing, determine whether or not is it worse with solids or liquids, and assess if it is worsens with fatigue (as expected).


1. Ask the patient or family to keep a headache record and note and score the associated symptoms;

2. If headaches or migraine - see HEADACHE.

  1. Autonomic dysregulation:
    1. Assess for autonomic dysfunction and those factors that can cause autonomic dysfunction: temperature dysregulation, abnormal (usually low) basal body temperature, heat and cold intolerance, abnormal sweating patterns, tachy- and bradycardia, dizziness, and bladder dysfunction.


a. Evaluate for vascular dysautonomia, and look for orthostatic changes in heart rate and blood pressure which can cause fatigue and dizziness.

b. Encourage fluids and/or calories. A trial of IV fluids might improve symptoms and support an autonomic etiology.


  1. Respiratory distress:

a. Note signs of respiratory distress. Patients or parents may describe dyspnea at rest or with minimum activity, or an inability "to catch their breath;

d. If gastroesophageal reflux is active, assess for aspiration causing respiratory distress;


1. Pulmonary function studies may be informative;

2. Assess for aspiration, if appropriate.

  1. Psychological causes:
    1. Assess for developmental or psychological issues that could impact intake.


1. Referral for psychological assessment if appropriate.


Debray FG, Lambert M, Chevalier I, et al. Long-term outcome and clinical spectrum of 73 pediatric patients with mitochondrial disease. Pediatrics 2007;119(4):722-33.

Gillis L, Kaye E. Diagnosis and management of mitochondrial disease. Pediatr Clinics N Am 2002;49(1):203-19.

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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