Ornithine carbamoyltransferase (OCT), formerly known as ornithine transcarbamoylase, catalyzes ornithine to citrulline in the urea cycle before its link with the citric acid cycle. Its importance stems from its role in the conversion of ammonia to urea by the liver. Decreased levels may be seen in inherited disorders associated with a partial block in the urea cycle.

• Hepatotoxic drugs and chemicals may produce elevated levels.

• Elevated serum ALP of uncertain etiology:
  • Elevated OCT levels are seen in viral hepatitis, cholecystitis, cirrhosis, cancer of the liver, and obstructive jaundice.
• Therapy with hepatotoxic drugs or exposure to hepatotoxic chemicals, with early effects indicated by elevated OCT levels
• Suspected mushroom poisoning as indicated by elevated levels

Nursing Care Before the Procedure

Client preparation is the same as that for any study involving collection of a peripheral blood sample (see Appendix I).

• Because many drugs may alter OCT levels, a medication history should be obtained. It is recommended that any drugs that may alter test results be withheld for 24 hours before the test, although this practice should be confirmed with the person ordering the study.

A venipuncture is performed and the sample collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Resume any drugs withheld before the test, pending test results.