A novel method for measuring serum ornithine carbamoyltransferase

Background Serum ornithine carbamoyltransferase is a diagnostic marker of hepatic disorders due to its localization in periportal mitochondria. Methods We have developed a new method for the determination of serum ornithine carbamoyltransferase. It is based on the reverse reaction of ornithine carbamoyltransferase, using ornithine - ketoacid aminotransferase, ¢ 1 -pyrroline-5carboxylate dehydrogenase and glutamate dehydrogenase, which together convert citrulline through ornithine to glutamate. The glutamate is then quantitatively measured using glutamate oxidase and Trinder’s reagent. Results The results obtained by this method agreed well with those obtained using the diacetylmonoxime method as a gold standard [correlation coef ecient (r) ˆ 0¢973 P50¢001]. The endogenous amino acids sensitive to this method in serum (glutamate, ornithine and ¢ 1 -pyrroline-5-carboxylate) were eliminated by the initial futile reaction. The new method appears to be more accurate at low levels of ornithine carbamoyltransferase activity than the diacetylmonoxime method. Conclusions Here we report a new method for serum ornithine carbamoyltransferase assay which might be useful for clinical diagnosis of hepatic disorders, including hepatic cancer. Ann Clin Biochem 2003; 40: 264‐268