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Neonatal hyperammonemia associated with carnitine deficiency
M Nagao1, A Tsuchiyama, T Mori
1Department of Pediatrics, Sapporo Medical College, Japan.
The Tohoku Journal of Experimental Medicine
|August 1, 1989
Summary
This study details a neonatal hyperammonemia case linked to secondary carnitine deficiency. L-carnitine treatment proved effective, highlighting its role in managing this rare metabolic disorder.
Area of Science:
- Biochemistry
- Pediatrics
- Metabolic Disorders
Background:
- Neonatal hyperammonemia is a critical condition requiring prompt diagnosis and management.
- Secondary carnitine deficiency can manifest with severe metabolic derangements, including hyperammonemia and acidosis.
- Urea cycle enzymopathies and organic acidemias are common causes of hyperammonemia, necessitating differential diagnosis.
Observation:
- A neonate presented with hyperammonemia shortly after birth, followed by severe metabolic acidosis at two months.
- Treatment with L-carnitine (100 mg/kg/day) successfully resolved the acidosis, but hyperammonemia recurred with increased protein intake, requiring a higher L-carnitine dose (150 mg/kg/day).
- Laboratory investigations excluded urea cycle defects and showed normal urinary organic acids, but revealed decreased serum, urine, and muscle carnitine levels.
Findings:
- The patient exhibited secondary carnitine deficiency as the cause of neonatal hyperammonemia and metabolic acidosis.
- Family history revealed a sibling who died from similar symptoms in the neonatal period, also found to have carnitine deficiency.
- Specific enzyme defects underlying the secondary carnitine deficiency could not be identified, suggesting a need for further biochemical investigation.
Implications:
- This case underscores the importance of considering secondary carnitine deficiency in neonates with unexplained hyperammonemia and metabolic acidosis.
- Timely L-carnitine supplementation can be life-saving in such cases.
- Further research is needed to elucidate the specific biochemical pathways leading to secondary carnitine deficiency in this family and potentially other affected individuals.