Urea Cycle Disorders

Urea Cycle Disorders are rare life-threatening genetic disorders present from birth. In Urea Cycle Disorders, the body is unable to break down the waste that is made from breaking down protein. Everyone needs protein. When a person eats foods that contain protein, the body breaks it down into amino acids and uses what it needs. It changes the rest into ammonia, which must be removed from the body. Normally, the liver changes ammonia into urea, which is then removed from the body in urine. In Urea Cycle Disorders, the liver is missing an enzyme to change ammonia into urea. As a result, ammonia, a highly toxic substance, builds up in the blood and can cause problems.

Some children have a mild form of Urea Cycle Disorder, some have a severe form. Some are not diagnosed until adulthood.

At present, the treatment for Urea Cycle Disorders is a protein restricted diet for life. Special amino acids, vitamins and minerals may be recommended. Some children will need to take medications such as sodium benzoate or sodium phenylbutyrate to help take extra ammonia out of the body.

During times of illness, the body will break down its own tissue to provide energy (catabolism). This can be dangerous for people with Urea Cycle Disorders as levels of ammonia and other harmful substances will increase quickly. Patients will have an individualised emergency plan to use when they are unwell.

At NCIMD, we have been treating patients with Urea Cycle Disorders for a number of decades and have significant experience of managing this disorder. Patients with Urea Cycle Disorders are managed by the multidisciplinary team and we liaise closely with the Metabolic Laboratory to ensure close monitoring of these patients. We follow international best practise guidelines and we collaborate with our international colleagues in the management of our patients with Urea Cycle Disorders.

Printable Resources

Urea Cycle Disorder Standard Emergency Letter

Urea Cycle Disorder Handbook
1 gram Exchange list 2023
Slightly Higher Exchange List 2023-for those on more than 7 exchanges
Super High Exchange List 2023-for those on more than 20 exchanges
Low Protein Manufactured Food List 2024
Reading food labels for other protein disorders

Weaning your baby on a diet for Urea Cycle Disorder