Link to the citric acid cycle:

 The synthesis of fumarate through argininosuccinase links the urea cycle to the citric acid cycle. Fumarate is an intermediate of this latter cycle which is then hydrated to malate, that in turn is oxidized to oxaloacetate.

Figure:  The urea cycle. The enzymes involved in this cycle are: (1) carbamoyl phosphate synthetase; (2) ornithine transcarbamoylase; (3) argininosuccinate synthetase; (4) arginosuccinase; and (5) arginase.

Oxaloacetate has various possible fates:

-  transamination to aspartate that can then feed back into the urea cycle;

-  to form citrate condensation with acetyl CoA that then continues on round the citric acid cycle;

-  By gluconeogenesis conversion into glucose;

-  conversion into pyruvate.