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, Delta(1)-pyrroline-5-carboxylate 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 coefficient (r) = 0.973 P<0.001]. The endogenous amino acids sensitive to this method in serum (glutamate, ornithine and Delta(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 carbamoyl-transferase assay which might be useful for clinical diagnosis of hepatic disorders, including hepatic cancer.