pediatrics
Urea Cycle Disorders
Treatment ofUreaCycle Disorders
Dietary protein restriction Arginineor citrulline supplementation Sodium phenylbutyrate Possible liver transplantation Treatment ofureacycle disorders is dietary protein restriction that still provides adequate amino acids for growth, development, and normal protein turnover. Argininehas become a staple of treatment. It supplies adequateureacycle intermediates to encourage the incorporation of more nitrogen moieties intoureacycle intermediates, each of which is readily excretable.Arginineis also a positive regulator of acetylglutamate synthesis. Recent studies suggest that oral citrulline is more effective thanargininein patients with OTC deficiency. Additional treatment is with sodium benzoate, phenylbutyrate, or phenylacetate, which by conjugatingglycine(sodium benzoate) and glutamine (phenylbutyrate and phenylacetate) provides a “nitrogen sink.” Despite these therapeutic advances, many UCDs remain difficult to treat, and liver transplantation is eventually required for many patients. Timing of liver transplantation is critical. Optimally, the infant should grow to an age when transplantation is less risky (>1 year), but it is important to not wait so long as to allow an intercurrent episode of hyperammonemia (often associated with illness) to cause irreparable harm to the central nervous system. 