Serum and tissue carnitine assay based on dialysis
Shihabi, Z.K.; Oles, K.S.; McCormick, C.P.; Penry, J.K.
Clinical Chemistry 38(8 Pt 1): 1414-1417
1992
ISSN/ISBN: 0009-9147 PMID: 1643708 Document Number: 402654
Carnitine (L-.beta.-hydroxy-.gamma.-trimethylaminobutyric acid) aids mitochondrial energy production by transferring fatty acids across the membranes for .beta.-oxidation. We describe here a modified enzymatic assay for free serum and tissue carnitine based on dialysis to remove interfering substances in the serum, with subsequent conversion of carnitine to the acyl derivatives by carnitine acetyltransferase (EC 2.3.1.7) in the presence of 5.5'-dithiobis-(2-nitrobenzoic acid). The method compared well with a radioenzymatic assay. The reference interval for serum is 28-70 .mu.mol/L. Patients with advanced diabetes and those undergoing valproic acid treatment displayed lower mean values; a statistically significant number of them showed serum carnitine values below the reference interval. The method was also applied to carnitine measurement in cerebrospinal fluid and human tissues.