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Age-related variations in acylcarnitine and free carnitine concentrations measured by tandem mass spectrometry
Catia Testa Cavedon1, Pierre Bourdoux, Karl Mertens
1Newborn Screening Center, Laboratory of Pediatrics, Free University of Brussels, Brussels, Belgium. catia.cavedon@gmail.com
Insights
Age-related variations exist in acylcarnitine profiles. Using age-specific reference values for free carnitine and acylcarnitines may improve diagnosis of inherited metabolic disorders.
Area of Science:
- Biochemistry
- Clinical Chemistry
- Pediatrics
Background:
- Acylcarnitine profiles from dried blood spots are crucial for diagnosing inherited metabolic disorders in children.
- Reference values for these profiles have not been extensively evaluated for age-related variations.
Purpose of the Study:
- To investigate age-related variations in free carnitine and acylcarnitine concentrations.
- To assess the impact of these variations on diagnosing inherited metabolic disorders.
Main Methods:
- Analysis of free carnitine and acylcarnitines in dried blood spots from 433 healthy individuals across eight age groups using tandem mass spectrometry.
- Comparison of mean values across age groups, including cord blood, neonates, infants, children, and adults, against a control group.
Main Results:
- Free carnitine levels were significantly higher in older children compared to newborns (P <0.05).
- Several acylcarnitine concentrations were significantly lower in cord blood and older children than in the control group.
- Minor sex-related differences were observed.
Conclusions:
- While the risk of underdiagnosis using newborn values is small, age-related reference values can potentially impact the diagnosis and management of inherited metabolic disorders.
- Implementing age-specific reference ranges may enhance diagnostic accuracy for certain metabolic conditions.
Background:
The acylcarnitine profiles obtained from dried blood spots on "Guthrie cards" have been widely used for the diagnosis and follow-up of children suspected of carrying an inherited error of metabolism, but little attention has been paid to potential age-related variations in the reference values. In this study, we evaluated the variations in free carnitine and acylcarnitine concentrations with age, as measured by tandem mass spectrometry.
Methods:
Filter-paper blood spots were collected from 433 healthy individuals over a period of 17 months. Eight age groups were defined: cord blood, 3-6 days (control group), 15-55 days, 2-18 months, 19-59 months, 5-10 years, 11-17 years, and 18-54 years. Free carnitine and acylcarnitines were measured for each individual. Mean values were calculated for each age group and compared with those for the control group.
Results:
Free carnitine was significantly higher in older children than in newborns (P <0.05), but the concentrations of several acylcarnitines tended to be significantly lower in cord blood and in groups of older children than in the control group. Only minor sex-related differences were observed.
Conclusion:
Although the risk of underdiagnosis of fatty acid oxidation disorders with the use of newborn values as reference can be considered as small, in some circumstances the use of age-related reference values may have a potential impact on the diagnosis and management of inherited errors of metabolism.
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