[Assay of carnitine in plasma and urine of healthy adults].
OBJECTIVE
To determine the levels of carnitine in plasma and daily excretion of carnitine in urine of healthy adults so as to provide the reference standard for studying the changes of carnitine in patients.


METHODS
Carnitine in plasma and urine was assayed with high performance liquid chromatography (HPLC). The levels of total carnitine (TC), free carnitine (FC) and acetyl-carnitine (AC) in fasting plasma and the daily excretion of TC, FC and AC in urine were assayed in 40 healthy adults (20 men and 20 women) with standard diet.


RESULTS
Good linearity (r 2 > or = 0.999) was observed in assaying TC, FC and AC. The relative standard deviation (RSD) was lower than 9.1% and bias lower than 5.6%. It was showed that the plasmatic levels of TC, FC and AC in healthy men [(53.1 +/- 8.5), (41.2 +/- 6.1), (6.2 +/- 0.6) mumol/L] were significantly higher than those in healthy women [(45.4 +/- 5.6), (35.2 +/- 4.9), (5.7 +/- 0.7) mumol/L] (P = 0.002, 0.002, 0.035). The daily urinary excretion of TC, FC and AC in healthy men [(386.1 +/- 22.9), (180.5 +/- 31.8), (33.8 +/- 3.3) mumol] were also significantly higher than those in healthy women [(240.1 +/- 35.6), (112.7 +/- 22.6), (29.3 +/- 4.3) mumol] (P < 0.0005, < 0.0005, < 0.0005) when the adults were given standard diet. Both the plasmatic levels and the daily urinary excretion of TC, FC and AC were of significantly positive correlation with lean body mass (LBM) (r = 0.501-0.856). The (TC-FC)/FC ratios in plasma were 0.29 +/- 0.05 for male and 0.29 +/- 0.04 for female.


CONCLUSIONS
Good precision and accuracy were observed in assaying carnitine with HPLC. After standard diet, both the level of carnitine in fasting plasma and the daily urinary carnitine excretion of healthy adults were positively correlated with LBM.
Niu
Yu-jian
YJ
Department of Surgery, PUMC Hospital, CAMS, PUMC, Beijing 100730, China. niuyj2000@hotmail.com
Jiang
Zhu-ming
ZM
Shu
Hong
H
Li
Chun-feng
CF
Liu
Wei
W
Yao
Guo-xiang
GX
Jiang
Ji
J
Li
Jing-quan
JQ
Longo
A
A
D000108:Acetylcarnitine / Q000097:blood / Q000652:urine; D000328:Adult; D002331:Carnitine / Q000097:blood* / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D012737:Sex Factors
D000108:Acetylcarnitine; D002331:Carnitine