[Blood spot carnitine and acylcarnitine in newborn to adolescence: measured by tandem mass spectrometry].

OBJECTIVE: To determine the levels of blood spot carnitine and acylcarnitine in children aged 0-15 years by tandem mass spectrometry, offer basic data for evaluating carnitine nutritional status and diagnosing metabolic diseases of organic acid and fatty acid.
METHODS: The concentration of carnitine and acylcarnitines were measured in blood spot by tandem mass spectrometry using underivatized samples. The samples included those from 1376 perinatal neonates, 49 neonates above 1 week of life, 64 children aged up to 1 year and 401 children aged 1 year to 15 years. A few premature infants and low birth weight infants were involved in perinatal neonates without selection. Other samples were taken from mainly outdoor patients for little surgical preoperative examination. Patients suffering from fever, diarrhea, liver disease, severe fat-metabolic diseases were excluded from this study.
RESULTS: The concentrations of carnitine (C(0)); short-chain acylcarnitines (SC-AC), including acetyl (C(2)), propionyl (C(3)), malonyl (C(3)DC), butyryl (C(4)), methylmalonyl (C(4)DC), isovaleryl (C(5)), glutaryl (C(5)DC); middle-chain acylcarnitines (MC-AC), including hexanoyl (C(6)), hexanediol (C(6)DC), octylenoyl (C(8:1)), octanoyl (C(8)), decadienoyl (C(10:2)), decanoyl (C(10:1)), decanoyl (C(10)); total carnitine and acylcarnitines (TCAC)were lower in neonate, highest in 1-3 months of age, higher in 6-12 months of age, and kept at the same level between 2 and 15 years of age. The concentrations of total long-chain acylcarnitines (LC-AC), including lauren (C(12:1)), lauroyl (C(12)), tetradecanoyl (C(14:1)), tetradecanoyl (C(14)), 3-hydroxy-tetradecanoyl (C(14)OH), hexadecenoyl (C(16:1)), hexadecanoyl (C(16)), 3-hydroxy-hexadecanoyl (C(16)OH), 3-hydroxy-hexadecanoyl (C(16:1)OH), octadecadienoyl (C(18:2)), octadecenoyl (C(18:1)), octadecanoyl (C(18)), 3-hydroxy-octadecenoyl (C(18:1)OH), and 3-hydroxy-octadecanoyl (C(18)OH) were the highest in neonate, decreased gradually, and kept the same level between 2 and 15 years of age. The concentrations of C(0) (23.387 ± 7.702) µmol/L, (30.064 ± 8.252) µmol/L, (25.021 ± 6.630) µmol/L, of LC-AC (4.998 ± 1.557) µmol/L, (2.854 ± 0.821) µmol/L, (2.459 ± 0.553) µmol/L, of TCAC (43.497 ± 12.632) µmol/L, (49.013 ± 12.497) µmol/L, (39.656 ± 9.257) µmol/L were significantly different among the groups of neonate, up to 1 year and above 1 year (P < 0.01). The concentrations of C(0) (24.115 ± 7.715) µmol/L and TCAC (43.65 ± 5.252) µmol/L in perinatal male neonates were higher than that (22.696 ± 7.246) µmol/L, TCAC (41.90 ± 5.038) µmol/L in female neonates. The C(0)/TCAC ratio of neonatal group (54.0% ± 7.1%) was significantly lower than that in the children group (62.1% ± 6.1%, P < 0.05), LC-AC/TCAC (33.5% ± 6.0%), MC-AC/TCAC (1.3% ± 0.3%), SC-AC/TCAC (11.6% ± 2.5%)ratios of neonatal group were higher than that of children group respectively (30.1% ± 4.9%; 0.9% ± 0.6%; 6.5% ± 2.3%, P < 0.05).
CONCLUSIONS: Concentrations and profiles of carnitine and acylcarnitines change significantly during the first year of life, the age should be considered as a factor when evaluating carnitine nutritional status and diagnosing metabolic diseases of organic acid and fatty acid. Concentrations of carnitine and acylcarnitines were a little higher in male neonates than in female.