eMedicine Specialties > Pediatrics: Genetics and Metabolic Disease > Metabolic Diseases
Carnitine Deficiency: Follow-up
Updated: Jul 22, 2009
Follow-up
Further Inpatient Care
- Admit patients with carnitine deficiency for medical management of acute metabolic decompensation.
- Prescribe 10% dextrose in water at rates of 10 mg/kg/min or higher to achieve normal glucose concentrations. If the rate of glucose infusion is based on blood glucose level alone, it may underestimate carbohydrate demand because tissues are depleted of glycogen stores.
- Provide intravenous (IV) carnitine if the patient is known to have carnitine deficiency and a defect affecting the oxidation of long chain fatty acids has been excluded.
Further Outpatient Care
- Carefully monitor adequate carnitine dose in primary and secondary carnitine deficiencies by evaluating plasma carnitine levels during follow-up visits.
- Carefully review diet compliance in secondary carnitine deficiency, considering avoidance of fasting, intake of fat-restricted, high-carbohydrate diet, and other dietary supplements that may be needed, such as riboflavin or glycine.
- Treat infections aggressively.
Inpatient & Outpatient Medications
- Medications include carnitine for primary and secondary carnitine deficiency, as well as other cofactors that may be needed for different conditions associated with secondary carnitine deficiency (eg, riboflavin, coenzyme Q, biotin, hydroxocobalamin, betaine, glycine).
- If a seizure disorder has developed secondary to a past episode of hypoglycemia, valproic acid should not be used as an anticonvulsant.
Transfer
- Patients may require transfer to a tertiary care center in which a more specialized metabolic workup for further diagnostic evaluation can be performed.
Deterrence/Prevention
- Prevent fasting with frequent feedings to avoid triggering episodes of hypoglycemia.
- Treat infections aggressively to prevent a catabolic state.
- Snacks and liquids should be consumed before exercise.
- Avoid exercise and dehydration with warm temperatures because attacks of rhabdomyolysis may occur with certain conditions that cause secondary carnitine deficiency.
- For fatty acid oxidation disorders, follow a fat-restricted diet with high carbohydrate content.
- Ensure uninterrupted carnitine supplementation.
Complications
- Dilated cardiomyopathy with congestive heart failure and pericardial effusion
- Sudden infant death syndrome (SIDS)
- Rhabdomyolysis with myoglobinuria and secondary renal failure
- Hypotonia
- Hypochromic microcytic anemia
- Failure to thrive
- GI dysmotility
- Pigmentary retinopathy
- Peripheral neuropathy
- CNS dysfunction with developmental delay, pyramidal signs, and athetoid movements
Prognosis
- Primary carnitine deficiency
- Patients with primary carnitine deficiency have excellent prognosis with oral carnitine supplementation.
- If the disorder is unrecognized, mortality may occur from cardiac failure, arrhythmias, or sudden death.
- Lifelong treatment with L-carnitine and avoidance of fasting are required. Hypoglycemia or sudden deaths from arrhythmias (even without cardiomyopathy) have been reported in patients who stop their carnitine supplementation against medical advice.
- Secondary carnitine deficiency
- Prognosis of secondary carnitine deficiency depends on the nature of the disorder.
- Translocase deficiency and the infantile form of carnitine palmitoyltransferase II (CPT-II) deficiency have very poor prognosis regardless of treatment.
- In general, disorders of fatty acid oxidation require lifelong prevention of fasting and diet modification.
- Other metabolic disorders that cause secondary carnitine deficiency, such as organic acidemias, require lifelong diet modification and nutritional supplements.
Patient Education
- Family members should receive education once the work-up initiated after newborn screening results suggests primary carnitine deficiency in the newborn or in the mother.
- Family members should receive cardiopulmonary resuscitation (CPR) training (cases of apnea or near-miss SIDS).
- Family members should be taught to recognize early signs and symptoms of hypoglycemia and should be instructed to provide either glucose gel or glucagon injection while waiting for emergency aid.
- Educate family members about frequent feedings and avoidance of fasting in general. If oral intake is decreased or poor, the child should be seen immediately at pediatrician's office or rushed to the emergency room.
- Educate family members about the importance of continuing carnitine supplementation.
- Educate family members about adhering to fat-restricted diet in fatty acid oxidation disorders or special protein-restricted diet in organic acidemias causing secondary carnitine deficiency.
- Refer parents for genetic counseling and discussion of recurrence risk for future pregnancies.
- Educate family members about the possibility of prenatal diagnosis. If the molecular defect has been established in the proband (primary carnitine deficiency or medium-chain acyl-CoA dehydrogenase [MCAD] deficiency), molecular analysis can be performed.
Miscellaneous
Medicolegal Pitfalls
- Failure to detect primary carnitine deficiency through the newborn screening program, as tandem mass spectrometry is used to detect low levels of free carnitine (C0)
- Failure to test the mother in the event of a low newborn screening carnitine level
- Failure to investigate primary or secondary carnitine deficiency as a cause of dilated cardiomyopathy, possibly creating delays in treatment and unnecessary evaluation for cardiac transplantation
- Failure to recognize other associated presentations, such as hypoketotic hypoglycemia, possibly placing the patient at risk for further CNS dysfunction or death
- Failure to inform the family about carnitine supplementation and dietary restrictions
- Failure to recognize or evaluate for other complications from causes of secondary carnitine deficiency, such as pigmentary retinopathy and progressive sensorimotor neuropathy
- Failure to recognize that supplementation with low doses of carnitine may improve nitrogen balance and growth in preterm newborns who are at risk for developing secondary carnitine deficiency
Special Concerns
- Acute fatty liver of pregnancy and the hemolysis, elevated liver enzyme levels, low platelet count (HELLP) syndrome are serious hepatic conditions that may occur during pregnancy in heterozygous women whose fetuses are later found to have a long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency.
- Hepatic carnitine palmitoyltransferase I deficiency may present as maternal illness during pregnancy.
- Individuals who are heterozygous for mutations in the OCTN2 gene responsible for primary carnitine deficiency are predisposed to late-onset benign cardiac hypertrophy; however, a recent study indicated that heterozygosity for primary carnitine deficiency is not more frequent in patients with unselected types of cardiomyopathy and may be unlikely to be an important cause of cardiomyopathy in adults.
- Premature infants are at risk for developing secondary carnitine deficiency if they are given parenteral nutrition with no L-carnitine supplementation. Secondary carnitine deficiency develops because of increased renal losses and immature biosynthesis of carnitine.
- Maternal primary carnitine deficiency may be underreported because the low C0 levels in newborns could be considered false positive results if the confirmatory testing is restricted to the infant.
More on Carnitine Deficiency |
| Overview: Carnitine Deficiency |
| Differential Diagnoses & Workup: Carnitine Deficiency |
| Treatment & Medication: Carnitine Deficiency |
 Follow-up: Carnitine Deficiency |
| References |
| « Previous Page |
References
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Further Reading
Keywords
carnitine deficiency, CD, primary carnitine deficiency, maternal carnitine deficiency, expanded newborn screening, myopathic carnitine deficiency, secondary carnitine deficiency, carnitine deficiency limited to the muscle, primary systemic carnitine deficiency, lipid-storage disease
lipid metabolism disorder, L-carnitine, hydrophilic amino acid derivative, progressive cardiomyopathy, hypoglycemia hypoketotic encephalopathy, fatty acid oxidation disorders, organic acidemias, ventricular fibrillation, ventricular tachycardia, heart failure, dilated cardiomyopathy, medium-chain acyl-CoA dehydrogenase deficiency, MCAD deficiency, heart myopathy, skeletal myopathy, hepatomegaly, hyperammonemia, gastrointestinal dysmotility, lipid storage myopathy, renal Fanconi tubulopathy
valproic acid, fulminant liver failure, Reye syndrome, pigmentary retinopathy, peripheral neuropathy, cardiac arrhythmias, myoglobinuria, glutaric aciduria type II deficiency, carnitine palmitoyltransferase II deficiency, CPT-II deficiency, mid-facial hypoplasia, frontal bossing, Zellwegerlike phenotype, congenital abnormalities of the abdominal wall, Fanconi syndrome, Lowe syndrome, cystinosis, lysinuric protein intolerance, propionic acidemia
methylmalonic acidemia, aminoacidopathies, isovaleric acidemia, propionic acidemia, methylmalonic acidemia, glutaric acidemia type I, 3-hydroxymethylglutaryl-CoA lyase deficiency, urea cycle defects, ornithine transcarbamylase deficiency, carbamoyl phosphate synthetase deficiency, X-linked oculocerebrorenal syndrome, chronic renal failure, cirrhosis, lacto-ovo–vegetarian diet, malabsorption syndromes, valproate, pivampicillin, emetine, zidovudine
