Age-Related Variations in Acylcarnitine and Free Carnitine Concentrations Measured by Tandem Mass Spectrometry

Abstract

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

Newborn screening for methylmalonic acidurias—Optimization by statistical parameter combination

“…According to the scarce literature available, levels of C 16:1 OH seem not to be influenced significantly by gestational age (Meyburg et al 2002) or those of C 16:1 OH and C 4 DC by the age at sampling (Cavedon et al 2005) and our patients_ data confirm this.…”

Postprandial changes of amino acid and acylcarnitine concentrations in dried blood samples

“…These differences, such as age at blood collection, birth weight, or gestational age, could be overcome by age, birth weight, and gestational-age-related reference values. However, only few publications on these data exist, and they often take only the variation of a single variable into account (Cavedon et al 2005, Meyburg et al 2001, Chace et al 2003, Honzík et al 2005, Corte and Venta 2010, Duran 2008, Matern 2008. The influence of some medications, such as dopamine and steroids upon thyroid-stimulating hormone (TSH) (Wilber and Utiger 1969, Brabant et al 1989, Haugen 2009) and 17α-hydroxyprogesterone (17-OHP), respectively, is well known (Rohrer et al 2003).…”

Detection of Pivaloylcarnitine in Pediatric Patients with Hypocarnitinemia after Long-Term Administration of Pivalate-Containing Antibiotics

“…Figures 3A and B show corresponding levels in Patient 2. At the time of admission, the serum free carnitine level was 1.0 µ mol/l in Patient 1 and 0.4 µ mol/l in Patient 2; these values were less than one-tenth of the normal levels for this age [33.3-43.0 µ mol/l (Cavedon et al 2005)]. By contrast, the serum pivaloylcarnitine levels were 3.7 and 1.6 µ mol/l in Patients 1 and 2, respectively, accounting for more than 70% of the total serum carnitine, which was calculated as the sum of the concentrations of free carnitine and all acylcarnitines detected in the serum.…”